including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole ...including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.展开更多
Within the relativistic mean field （RMF） theory, the ground state properties of dysprosium isotopes are studied using the shell-model-like approach （SLAP）, in which pairing correlations are treated with particle- ...Within the relativistic mean field （RMF） theory, the ground state properties of dysprosium isotopes are studied using the shell-model-like approach （SLAP）, in which pairing correlations are treated with particle- number conservation, and the Pauli blocking effects are taken into account exactly. For comparison, calculations of the Bardeen Cooper Schrieffer （BCS） model with the RMF are also performed. It is found that the RMF＋SLAP calculation results, as well as the RMF＋BCS ones, reproduce the experimental binding energies and one- and twoneutron separation energies quite well. However, the RMF＋BCS calculations give larger pairing energies than those obtained by the RMF＋SLAP calculations, in particular for nuclei near the proton and neutron drip lines. This deviation is discussed in terms of the BCS particle-number fluctuation, which leads to the sizable deviation of pairing energies between the RMF＋BCS and RMF＋SLAP models, where the fluctuation of the particle number is eliminated automatically.展开更多
The effects of pairing correlation in Yb isotopes are investigated by covariant density functional theory with pairing correlations and blocking effects treated exactly by a shell model like approach （SLAP）. Experim...The effects of pairing correlation in Yb isotopes are investigated by covariant density functional theory with pairing correlations and blocking effects treated exactly by a shell model like approach （SLAP）. Experimental one- and two-neutron separation energies are reproduced quite well. The traditional BCS calculations always give larger pairing energies than those given by SLAP calculations, particularly for the nuclei near the proton and neutron drip lines. This may be caused because many of the single particle orbits above the Fermi surface are involved in the BCS calculations, but many of them are excluded in the SLAP calculations.展开更多
Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural...Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural network based machine-learning pipeline that effectively predicts structure-property relationship of amorphous material via global descriptors.Applying SPRamNet on the recently discovered amorphous monolayer carbon,we successfully predict the thermal and electronic properties.More importantly,we reveal that a short range of pair correlation function can readily encode sufficiently rich information of the structure of amorphous material.Utilizing powerful machine learning architectures,the encoded information can be decoded to reconstruct macroscopic properties involving many-body and long-range interactions.Establishing this hidden relationship offers a unified description of the degree of disorder and eliminates the heavy burden of measuring atomic structure,opening a new avenue in studying amorphous materials.展开更多
A new model for self-diffusion coefficients was proposed based oil both the concepts of molecular free volume and activation energy. The unknown parameters of this model were clearly defined and compared with the Chap...A new model for self-diffusion coefficients was proposed based oil both the concepts of molecular free volume and activation energy. The unknown parameters of this model were clearly defined and compared with the Chapman-Enskog model. At the same time a new method for calculating activation energy was devised and applied to the new model. In addition, the free volume was defined by implementing the generic van der Waals equation of state, the radial distribution function of which was obtained by using the Morsali- Goharshadi empirical formula. Under the same conditions, the new model was better than the original free volume model.展开更多
The contribution of the resonant continuum to pairing correlations is investigated in the relativistic mean field theory plus Bardeen–Cooper–Schrieffer (BCS) approximation with a constant pairing strength. The reson...The contribution of the resonant continuum to pairing correlations is investigated in the relativistic mean field theory plus Bardeen–Cooper–Schrieffer (BCS) approximation with a constant pairing strength. The resonance states with their widths in the continuum are considered explicitly. The numerical study is performed in an effective Lagrangian with the parameter set NLSH for neutron-rich nucleus <SUP>84</SUP>Ni. The results show that the effect of the proper treatment of the resonant continuum on pairing correlations for nucleus close to neutron drip line is important. It is found that the problem of an unphysical particle gas could be overcome when the pairing correlation is performed by using the resonant states instead of the discretized states in the continuum.展开更多
For accurate Finite Element(FE)modeling for the structural dynamics of aeroengine casings,Parametric Modeling-based Model Updating Strategy(PM-MUS)is proposed based on efficient FE parametric modeling and model updati...For accurate Finite Element(FE)modeling for the structural dynamics of aeroengine casings,Parametric Modeling-based Model Updating Strategy(PM-MUS)is proposed based on efficient FE parametric modeling and model updating techniques regarding uncorrelated/correlated mode shapes.Casings structure is parametrically modeled by simplifying initial structural FE model and equivalently simulating mechanical characteristics.Uncorrelated modes between FE model and experiment are reasonably handled by adopting an objective function to recognize correct correlated modes pairs.The parametrized FE model is updated to effectively describe structural dynamic characteristics in respect of testing data.The model updating technology is firstly validated by the detailed FE model updating of one fixed–fixed beam structure in light of correlated/uncorrelated mode shapes and measured mode data.The PM-MUS is applied to the FE parametrized model updating of an aeroengine stator system(casings)which is constructed by the proposed parametric modeling approach.As revealed in this study,(A)the updated models by the proposed updating strategy and dynamic test data is accurate,and(B)the uncorrelated modes like close modes can be effectively handled and precisely identify the FE model mode associated the corresponding experimental mode,and(C)parametric modeling can enhance the dynamic modeling updating of complex structure in the accuracy of mode matching.The efforts of this study provide an efficient dynamic model updating strategy(PM-MUS)for aeroengine casings by parametric modeling and experimental test data regarding uncorrelated modes.展开更多
In structural simulation and design,an accurate computational model directly determines the effectiveness of performance evaluation.To establish a high-fidelity dynamic model of a complex assembled structure,a Hierarc...In structural simulation and design,an accurate computational model directly determines the effectiveness of performance evaluation.To establish a high-fidelity dynamic model of a complex assembled structure,a Hierarchical Model Updating Strategy(HMUS)is developed for Finite Element(FE)model updating with regard to uncorrelated modes.The principle of HMUS is first elaborated by integrating hierarchical modeling concept,model updating technology with proper uncorrelated mode treatment,and parametric modeling.In the developed strategy,the correct correlated mode pairs amongst the uncorrelated modes are identified by an error minimization procedure.The proposed updating technique is validated by the dynamic FE model updating of a simple fixed–fixed beam.The proposed HMUS is then applied to the FE model updating of an aeroengine stator system(casings)to demonstrate its effectiveness.Our studies reveal that(A)parametric modeling technique is able to build an efficient equivalent model by simplifying complex structure in geometry while ensuring the consistency of mechanical characteristics;(B)the developed model updating technique efficiently processes the uncorrelated modes and precisely identifies correct Correlated Mode Pairs(CMPs)between FE model and experiment;(C)the proposed HMUS is accurate and efficient in the FE model updating of complex assembled structures such as aeroengine casings with large-scale model,complex geometry,high-nonlinearity and numerous parameters;(D)it is appropriate to update a complex structural FE model parameterized.The efforts of this study provide an efficient updating strategy for the dynamic model updating of complex assembled structures with experimental test data,which is promising to promote the precision and feasibility of simulation-based design optimization and performance evaluation of complex structures.展开更多
A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified pa...A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified partially hydrolyzed polyacrylamide （HM-HPAM） such as radius of gyration （Rg）, hydrodynamic radius （RH）, and radial distribution functions （RDFs） have been studied to find the intrinsic relation between the microstructure of the polymer chain and the intrinsic viscosities with changing the amotmt of modified monomers from 1% to 4%. The simulation results show that, compared to HPAM, HM-HPAM has a better performance in increasing viscosity when the percentage of modified monomers is 2% and has a stronger salt tolerance when the modified monomers is 4%. Furthermore, a complex hydrogen bonding network was revealed with the analysis of radial distribution functions （RDFs） and the pair correlation function was used to investigate the diffusivity of Na^＋ and carbon atoms in the COO^- group.展开更多
A comprehensive evaluation model based on improved set pair analysis is established. Considering the complexity in decision-making process, the model combines the certainties and uncertainties in the schemes, i.e., id...A comprehensive evaluation model based on improved set pair analysis is established. Considering the complexity in decision-making process, the model combines the certainties and uncertainties in the schemes, i.e., identical degree, different degree and opposite degree. The relations among different schemes are studied, and the traditional way of solving uncertainty problem is improved. By using the gray correlation to determine the difference degree, the problem of less evaluation indexes and inapparent linear relationship is solved. The difference between the evaluation parameters is smaller in both the fuzzy comprehensive evaluation model and fuzzy matter-element method, and the dipartite degree of the evaluation result is unobvious. However, the difference between each integrated connection degree is distinct in the improved set pair analysis. Results show that the proposed method is feasible and it obtains better effects than the fuzzy comprehensive evaluation method and fuzzy matter-element method.展开更多
We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by mic...We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by microscopic theory, Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations. Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.展开更多
With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a ...With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a quantitative level in very fine details for a prototypical A+BC system. As the system becomes larger, more degrees of freedom are involved and the complexity increases exponentially. At the same time, the multifaceted nature of polyatomic systems also opens up the possibilities for observing many new chemistry and novel phenomena|a land of opportunities. For the past 15 years or so my laboratory has delved into the reaction dynamics of methane+X (X: F, Cl, O(3P), and OH). This effort shifts the paradigm in the field of reaction dynamics by making the title reaction a benchmark polyatomic system. In this account, I shall disclose my thinking behind some of the key concepts and methods we introduced and how the unexpectedly discovered phenomena led to other uncharted territories. Those ndings not only enrich our understanding of the specific reactions we studied at the most fundamental level and inspire the theoretical developments, but also shape our thinking and lay the foundation for future explorations of different aspects of the multifaceted nature of polyatomic reactivity.展开更多
The pair correlation energy of bonding electrons is used and analyzed in the cal- culation of CH and CY (Y = F, O, N) bonding electron pairs in CH3X (X = F, OH, NH2) isoelec- tronic systems based on intra- and interpa...The pair correlation energy of bonding electrons is used and analyzed in the cal- culation of CH and CY (Y = F, O, N) bonding electron pairs in CH3X (X = F, OH, NH2) isoelec- tronic systems based on intra- and interpair correlation energy results at both MP2-OPT2/6- 311++G(d) and MP2-OPT2/cc-pVtz levels with MELD program. Comparison of two set results shows that cc-pVtz and 6-311++G(d) give more correlation energy of valence electrons and innermost core electron pairs, respectively in these systems, resulting that the total correlation energy with cc-pVtz basis of each system is larger than that with 6-311++G(d). Investigations of pair correlation energy show that with the decrease of electronegativity of X atom and the increase of H atoms in these CH3X (X = F, OH, NH2) systems, the pair correlation energy of 1sC2 of the C atoms is transferable, and the correlation energy of CH bonding electron pair with little changes is of approximate transferability, while those of CY (CF, CO, CN) bonding electron pair decrease in a large extent from CH3F through CH3OH to CH3NH2 molecules. It is suggested that the study of pair correlation energy of bonding electrons will further deepen the understanding of electron corre- lation effect from traditional chemical bonding concept.展开更多
We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole...We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole resonances(PDR)in^(68)Ni and^(132)Sn.The calculations are performed within the Skyrme HF(or HF+BCS)plus random phase approximation(RPA)(or quasiparticle RPA)problem using SAMi-J effective interactions.The effect of pairing on the dipole strength distribution of^(68)Ni and density dependence of the symmetry energy is discussed.Slope parameter L and symmetry energy J at saturation(subsaturation)density are 41.8−90.2 MeV(39.3−64.1 MeV)and 28.0−32.5 MeV(23.0−23.8 MeV),respectively.They are consistent with the currently accepted values except for J at subsaturation density,which is slightly lower than the values obtained from nuclear mass difference measurements and electric dipole polarizability data.展开更多
The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory....The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.展开更多
The recently observed two high-spin rotational bands in the proton emitter ^113Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the P...The recently observed two high-spin rotational bands in the proton emitter ^113Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 [π3/2^＋[422]（g7/2）, α =-1/2] and band 2 [π1/2^＋[420]（d5/2）, α=1/2], the experimental moments of inertia and quasiparticle alignments can be reproduced much better by the present calculations than those using the configuration assginment of π1/2^-[550]（h11/2）, which in turn may support these configuration assignments. Furthermore, by analyzing the occupation probability nμ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.展开更多
The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the ...The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hw are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.展开更多
The α-cluster structures for 12^C and 16^O are investigated in the framework of the covariant density functional theory, where the pairing correlation is treated with a particle number conserving shell-model-like app...The α-cluster structures for 12^C and 16^O are investigated in the framework of the covariant density functional theory, where the pairing correlation is treated with a particle number conserving shell-model-like approach. The ground states of 12^C and 160 have been calculated and the density distributions demonstrate an equilateral triangle 3α clustering for 12^C and a regular tetrahedron 4α clustering for 16^O The existence of linear nα chain structure of both 12^C and 16^O is revealed at high quadrupole deformation.展开更多
Within the localized molecular orbital description,the intra- and interorbital pair correlation energies calculated with the coupled cluster doubles (CCD) theory have been obtained for methane,ethane,propane,butane,is...Within the localized molecular orbital description,the intra- and interorbital pair correlation energies calculated with the coupled cluster doubles (CCD) theory have been obtained for methane,ethane,propane,butane,isobutane,pentane, isopentane and neopentane using the 6-31G * basis set. The results showed the quantitative transferability of pair correlation energies and gross orbital correlation energies within this series of molecules. Based on the gross orbital correlation energies of five sample alkanes (butane,isobutane,pentane,isopentane and neopentane),we have derived a simple linear relationship to estimate the CCD correlation energy for an arbitrary large alkane. The correlation energy predicted by this simple relationship remarkably recovers more than 98.9% of the exact CCD correlation energy for a number of alkanes containing six to eight carbon atoms. The relative stability of less branched isomers can be correctly predicted.展开更多
In this work,we have performed Skyrme density functional theory(DFT)calculations of nuclei around^132Sn to study whether the abnormal odd-even staggering(OES)behavior of binding energies around N=82 can be reproduced....In this work,we have performed Skyrme density functional theory(DFT)calculations of nuclei around^132Sn to study whether the abnormal odd-even staggering(OES)behavior of binding energies around N=82 can be reproduced.With the Skyrme forces SLy4 and SkM*,we tested the volume-and surface-type pairing forces and also the intermediate between these two pairing forces,in the Hartree-Fock-Bogoliubov(HFB)approximation with or without the Lipkin-Nogami(LN)approximation or particle number projection after the convergence of HFBLN(PLN).The Universal Nuclear Energy Density Function(UNEDF)parameter sets are also used.The trend of the neutron OES against the neutron number or proton number does not change significantly by tuning the density dependence of the pairing force.Moreover,for the pairing force that is favored more at the nuclear surface,a larger mass OES is obtained,and vice versa.It appears that the combination of volume and surface pairing can give better agreement with the data.In the studies of the OES,a larger ratio of surface to volume pairing might be favored.Additionally,in most cases,the OES given by the HFBLN approximation agrees more closely with the experimental data.We found that both the Skyrme and pairing forces can influence the OES behavior.The mass OES calculated by the UNEDF DFT is explicitly smaller than the experimental one.The UNEDF1 and UNEDF2 forces can reproduce the experimental trend of the abnormal OES around^132Sn.The neutron OES of the tin isotopes given by the SkM*force agrees more closely with the experimental one than that given by the SLy4 force in most cases.Both SLy4 and SkM*DFT have difficulties in reproducing the abnormal OES around^132Sn.Using the PLN method,the systematics of OES are improved for several combinations of Skyrme and pairing forces.展开更多
文摘including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.
基金Supported by Fundamental Research Funds for the Central Universities(JUSRP1035)National Natural Science Foundation of China(11305077)
文摘Within the relativistic mean field （RMF） theory, the ground state properties of dysprosium isotopes are studied using the shell-model-like approach （SLAP）, in which pairing correlations are treated with particle- number conservation, and the Pauli blocking effects are taken into account exactly. For comparison, calculations of the Bardeen Cooper Schrieffer （BCS） model with the RMF are also performed. It is found that the RMF＋SLAP calculation results, as well as the RMF＋BCS ones, reproduce the experimental binding energies and one- and twoneutron separation energies quite well. However, the RMF＋BCS calculations give larger pairing energies than those obtained by the RMF＋SLAP calculations, in particular for nuclei near the proton and neutron drip lines. This deviation is discussed in terms of the BCS particle-number fluctuation, which leads to the sizable deviation of pairing energies between the RMF＋BCS and RMF＋SLAP models, where the fluctuation of the particle number is eliminated automatically.
基金Supported by"the Fundamental Research Funds for the Central Universities"(JUSRP1035)NSFC(11305077,11335002)
文摘The effects of pairing correlation in Yb isotopes are investigated by covariant density functional theory with pairing correlations and blocking effects treated exactly by a shell model like approach （SLAP）. Experimental one- and two-neutron separation energies are reproduced quite well. The traditional BCS calculations always give larger pairing energies than those given by SLAP calculations, particularly for the nuclei near the proton and neutron drip lines. This may be caused because many of the single particle orbits above the Fermi surface are involved in the BCS calculations, but many of them are excluded in the SLAP calculations.
基金supported by the National Key R&D Program of China under Grant No.2021YFA1400500the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDB33000000+1 种基金the National Natural Science Foundation of China under Grant No.12334003the Beijing Municipal Natural Science Foundation under Grant Nos.JQ22001 and QY23014。
文摘Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural network based machine-learning pipeline that effectively predicts structure-property relationship of amorphous material via global descriptors.Applying SPRamNet on the recently discovered amorphous monolayer carbon,we successfully predict the thermal and electronic properties.More importantly,we reveal that a short range of pair correlation function can readily encode sufficiently rich information of the structure of amorphous material.Utilizing powerful machine learning architectures,the encoded information can be decoded to reconstruct macroscopic properties involving many-body and long-range interactions.Establishing this hidden relationship offers a unified description of the degree of disorder and eliminates the heavy burden of measuring atomic structure,opening a new avenue in studying amorphous materials.
文摘A new model for self-diffusion coefficients was proposed based oil both the concepts of molecular free volume and activation energy. The unknown parameters of this model were clearly defined and compared with the Chapman-Enskog model. At the same time a new method for calculating activation energy was devised and applied to the new model. In addition, the free volume was defined by implementing the generic van der Waals equation of state, the radial distribution function of which was obtained by using the Morsali- Goharshadi empirical formula. Under the same conditions, the new model was better than the original free volume model.
文摘The contribution of the resonant continuum to pairing correlations is investigated in the relativistic mean field theory plus Bardeen–Cooper–Schrieffer (BCS) approximation with a constant pairing strength. The resonance states with their widths in the continuum are considered explicitly. The numerical study is performed in an effective Lagrangian with the parameter set NLSH for neutron-rich nucleus <SUP>84</SUP>Ni. The results show that the effect of the proper treatment of the resonant continuum on pairing correlations for nucleus close to neutron drip line is important. It is found that the problem of an unphysical particle gas could be overcome when the pairing correlation is performed by using the resonant states instead of the discretized states in the continuum.
基金co-supported by National Natural Science Foundation of China(Nos.51975124 and 51675179)Shanghai International Cooperation Project of One Belt and One Road of China(No.20110741700)Research Startup Fund of Fudan University(No.FDU38341)。
文摘For accurate Finite Element(FE)modeling for the structural dynamics of aeroengine casings,Parametric Modeling-based Model Updating Strategy(PM-MUS)is proposed based on efficient FE parametric modeling and model updating techniques regarding uncorrelated/correlated mode shapes.Casings structure is parametrically modeled by simplifying initial structural FE model and equivalently simulating mechanical characteristics.Uncorrelated modes between FE model and experiment are reasonably handled by adopting an objective function to recognize correct correlated modes pairs.The parametrized FE model is updated to effectively describe structural dynamic characteristics in respect of testing data.The model updating technology is firstly validated by the detailed FE model updating of one fixed–fixed beam structure in light of correlated/uncorrelated mode shapes and measured mode data.The PM-MUS is applied to the FE parametrized model updating of an aeroengine stator system(casings)which is constructed by the proposed parametric modeling approach.As revealed in this study,(A)the updated models by the proposed updating strategy and dynamic test data is accurate,and(B)the uncorrelated modes like close modes can be effectively handled and precisely identify the FE model mode associated the corresponding experimental mode,and(C)parametric modeling can enhance the dynamic modeling updating of complex structure in the accuracy of mode matching.The efforts of this study provide an efficient dynamic model updating strategy(PM-MUS)for aeroengine casings by parametric modeling and experimental test data regarding uncorrelated modes.
基金co-supported by National Natural Science Foundation of China(No.51975124)Shanghai International Cooperation Project of One Belt and One Road of China(No.20110741700)Major Research Special Project of Aeroengine and Gas Turbine of China(No.J2019-IV-0016)。
文摘In structural simulation and design,an accurate computational model directly determines the effectiveness of performance evaluation.To establish a high-fidelity dynamic model of a complex assembled structure,a Hierarchical Model Updating Strategy(HMUS)is developed for Finite Element(FE)model updating with regard to uncorrelated modes.The principle of HMUS is first elaborated by integrating hierarchical modeling concept,model updating technology with proper uncorrelated mode treatment,and parametric modeling.In the developed strategy,the correct correlated mode pairs amongst the uncorrelated modes are identified by an error minimization procedure.The proposed updating technique is validated by the dynamic FE model updating of a simple fixed–fixed beam.The proposed HMUS is then applied to the FE model updating of an aeroengine stator system(casings)to demonstrate its effectiveness.Our studies reveal that(A)parametric modeling technique is able to build an efficient equivalent model by simplifying complex structure in geometry while ensuring the consistency of mechanical characteristics;(B)the developed model updating technique efficiently processes the uncorrelated modes and precisely identifies correct Correlated Mode Pairs(CMPs)between FE model and experiment;(C)the proposed HMUS is accurate and efficient in the FE model updating of complex assembled structures such as aeroengine casings with large-scale model,complex geometry,high-nonlinearity and numerous parameters;(D)it is appropriate to update a complex structural FE model parameterized.The efforts of this study provide an efficient updating strategy for the dynamic model updating of complex assembled structures with experimental test data,which is promising to promote the precision and feasibility of simulation-based design optimization and performance evaluation of complex structures.
基金financially supported by the National Natural Science Foundation of China(No.20904035)
文摘A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified partially hydrolyzed polyacrylamide （HM-HPAM） such as radius of gyration （Rg）, hydrodynamic radius （RH）, and radial distribution functions （RDFs） have been studied to find the intrinsic relation between the microstructure of the polymer chain and the intrinsic viscosities with changing the amotmt of modified monomers from 1% to 4%. The simulation results show that, compared to HPAM, HM-HPAM has a better performance in increasing viscosity when the percentage of modified monomers is 2% and has a stronger salt tolerance when the modified monomers is 4%. Furthermore, a complex hydrogen bonding network was revealed with the analysis of radial distribution functions （RDFs） and the pair correlation function was used to investigate the diffusivity of Na^＋ and carbon atoms in the COO^- group.
基金Supported by Foundation for Innovative Research Groups of National Natural Science Foundation of China(No.51021004)Tianjin Research Program of Application Foundation and Advanced Technology(No.12JCZDJC29200)National Key Technology R&D Program in the 12th Five-Year Plan of China(No.2011BAB10B06)
文摘A comprehensive evaluation model based on improved set pair analysis is established. Considering the complexity in decision-making process, the model combines the certainties and uncertainties in the schemes, i.e., identical degree, different degree and opposite degree. The relations among different schemes are studied, and the traditional way of solving uncertainty problem is improved. By using the gray correlation to determine the difference degree, the problem of less evaluation indexes and inapparent linear relationship is solved. The difference between the evaluation parameters is smaller in both the fuzzy comprehensive evaluation model and fuzzy matter-element method, and the dipartite degree of the evaluation result is unobvious. However, the difference between each integrated connection degree is distinct in the improved set pair analysis. Results show that the proposed method is feasible and it obtains better effects than the fuzzy comprehensive evaluation method and fuzzy matter-element method.
文摘We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by microscopic theory, Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations. Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.
基金Academia Sinicathe Minster of Science and Technology of Taiwan (formerly, the National Science of Council) for their generous financial supports
文摘With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a quantitative level in very fine details for a prototypical A+BC system. As the system becomes larger, more degrees of freedom are involved and the complexity increases exponentially. At the same time, the multifaceted nature of polyatomic systems also opens up the possibilities for observing many new chemistry and novel phenomena|a land of opportunities. For the past 15 years or so my laboratory has delved into the reaction dynamics of methane+X (X: F, Cl, O(3P), and OH). This effort shifts the paradigm in the field of reaction dynamics by making the title reaction a benchmark polyatomic system. In this account, I shall disclose my thinking behind some of the key concepts and methods we introduced and how the unexpectedly discovered phenomena led to other uncharted territories. Those ndings not only enrich our understanding of the specific reactions we studied at the most fundamental level and inspire the theoretical developments, but also shape our thinking and lay the foundation for future explorations of different aspects of the multifaceted nature of polyatomic reactivity.
基金Supported by the National Natural Science Foundation of China (No. 20173027 and No. 29873023)
文摘The pair correlation energy of bonding electrons is used and analyzed in the cal- culation of CH and CY (Y = F, O, N) bonding electron pairs in CH3X (X = F, OH, NH2) isoelec- tronic systems based on intra- and interpair correlation energy results at both MP2-OPT2/6- 311++G(d) and MP2-OPT2/cc-pVtz levels with MELD program. Comparison of two set results shows that cc-pVtz and 6-311++G(d) give more correlation energy of valence electrons and innermost core electron pairs, respectively in these systems, resulting that the total correlation energy with cc-pVtz basis of each system is larger than that with 6-311++G(d). Investigations of pair correlation energy show that with the decrease of electronegativity of X atom and the increase of H atoms in these CH3X (X = F, OH, NH2) systems, the pair correlation energy of 1sC2 of the C atoms is transferable, and the correlation energy of CH bonding electron pair with little changes is of approximate transferability, while those of CY (CF, CO, CN) bonding electron pair decrease in a large extent from CH3F through CH3OH to CH3NH2 molecules. It is suggested that the study of pair correlation energy of bonding electrons will further deepen the understanding of electron corre- lation effect from traditional chemical bonding concept.
基金Partly Supported by the National Natural Science Foundation of China(12275025,11975096,11875027,11775014)the Fundamental Research Funds for the Central Universities(2020NTST06)。
文摘We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole resonances(PDR)in^(68)Ni and^(132)Sn.The calculations are performed within the Skyrme HF(or HF+BCS)plus random phase approximation(RPA)(or quasiparticle RPA)problem using SAMi-J effective interactions.The effect of pairing on the dipole strength distribution of^(68)Ni and density dependence of the symmetry energy is discussed.Slope parameter L and symmetry energy J at saturation(subsaturation)density are 41.8−90.2 MeV(39.3−64.1 MeV)and 28.0−32.5 MeV(23.0−23.8 MeV),respectively.They are consistent with the currently accepted values except for J at subsaturation density,which is slightly lower than the values obtained from nuclear mass difference measurements and electric dipole polarizability data.
基金Supported by the National Natural Science Foundation of China(U1832120,11675265)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province,China(A2020210012)+4 种基金the Natural Science Foundation of Hebei Province,China(A2021210010)the Key Laboratory of High Precision Nuclear Spectroscopy,Institute of Modern Physics,Chinese Academy of Sciences(IMPKFKT2021002)the Graduate Student Innovative Research Project of Shijiazhuang Tiedao University(YC2022062)the Continuous Basic Scientific Research Project(WDJC-2019-13)the Leading Innovation Project(LC 192209000701).
文摘The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.
基金Supported by National Natural Science Foundation of China(11275098,11275248,11505058)Fundamental Research Funds for the Central Universities(2015QN21)
文摘The recently observed two high-spin rotational bands in the proton emitter ^113Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 [π3/2^＋[422]（g7/2）, α =-1/2] and band 2 [π1/2^＋[420]（d5/2）, α=1/2], the experimental moments of inertia and quasiparticle alignments can be reproduced much better by the present calculations than those using the configuration assginment of π1/2^-[550]（h11/2）, which in turn may support these configuration assignments. Furthermore, by analyzing the occupation probability nμ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2015QN21)the National Natural Science Foundation of China(Grant Nos.11275098,11275248,and 11505058)
文摘The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hw are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.
基金Supported by Major State Basic Research Development (973) Program (2007CB815000)NSFC (11175002,11105005)Research Fund for the Doctoral Program of Higher Education (20110001110087)
文摘The α-cluster structures for 12^C and 16^O are investigated in the framework of the covariant density functional theory, where the pairing correlation is treated with a particle number conserving shell-model-like approach. The ground states of 12^C and 160 have been calculated and the density distributions demonstrate an equilateral triangle 3α clustering for 12^C and a regular tetrahedron 4α clustering for 16^O The existence of linear nα chain structure of both 12^C and 16^O is revealed at high quadrupole deformation.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 0 73 0 2 0 )
文摘Within the localized molecular orbital description,the intra- and interorbital pair correlation energies calculated with the coupled cluster doubles (CCD) theory have been obtained for methane,ethane,propane,butane,isobutane,pentane, isopentane and neopentane using the 6-31G * basis set. The results showed the quantitative transferability of pair correlation energies and gross orbital correlation energies within this series of molecules. Based on the gross orbital correlation energies of five sample alkanes (butane,isobutane,pentane,isopentane and neopentane),we have derived a simple linear relationship to estimate the CCD correlation energy for an arbitrary large alkane. The correlation energy predicted by this simple relationship remarkably recovers more than 98.9% of the exact CCD correlation energy for a number of alkanes containing six to eight carbon atoms. The relative stability of less branched isomers can be correctly predicted.
基金Supported by National Natural Science Foundation of China(U1732138,11505056,11605054,11975209,11790325,11947410,11847315)the Outstanding Young Talent Research Fund of Zhengzhou University(152137002)。
文摘In this work,we have performed Skyrme density functional theory(DFT)calculations of nuclei around^132Sn to study whether the abnormal odd-even staggering(OES)behavior of binding energies around N=82 can be reproduced.With the Skyrme forces SLy4 and SkM*,we tested the volume-and surface-type pairing forces and also the intermediate between these two pairing forces,in the Hartree-Fock-Bogoliubov(HFB)approximation with or without the Lipkin-Nogami(LN)approximation or particle number projection after the convergence of HFBLN(PLN).The Universal Nuclear Energy Density Function(UNEDF)parameter sets are also used.The trend of the neutron OES against the neutron number or proton number does not change significantly by tuning the density dependence of the pairing force.Moreover,for the pairing force that is favored more at the nuclear surface,a larger mass OES is obtained,and vice versa.It appears that the combination of volume and surface pairing can give better agreement with the data.In the studies of the OES,a larger ratio of surface to volume pairing might be favored.Additionally,in most cases,the OES given by the HFBLN approximation agrees more closely with the experimental data.We found that both the Skyrme and pairing forces can influence the OES behavior.The mass OES calculated by the UNEDF DFT is explicitly smaller than the experimental one.The UNEDF1 and UNEDF2 forces can reproduce the experimental trend of the abnormal OES around^132Sn.The neutron OES of the tin isotopes given by the SkM*force agrees more closely with the experimental one than that given by the SLy4 force in most cases.Both SLy4 and SkM*DFT have difficulties in reproducing the abnormal OES around^132Sn.Using the PLN method,the systematics of OES are improved for several combinations of Skyrme and pairing forces.
