Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order po...Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg2 are studied by the coupled cluster theory with spin-orbit coupling. Spin-orbit coupling is included in the post Hartree-Fock procedure, i.e., in the coupled- cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg2.展开更多
The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q,...The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q, 5, or 6), complete basis set extrapolation functions with two-parameters and three-parameters, together with considering the contributions due to the core-valence electron correlation, scalar relativistic effects, spin–orbit coupling, and zero-point vibrational corrections. Our calculations show that both the neutral S_3 and anion S_3^- have open forms with C_(2r) vsymmetry. On the basis of the stable geometries, the adiabatic electron affinity of S_3 is determined to be 19041(11) cm^(-1), which is in excellent agreement with the experimental data(19059(7) cm^(-1)). The dependence of geometries and electron affinity on the computation level and physical corrections is discussed. The present computational results are helpful to the experimental molecular spectroscopy and bonding of S_3.展开更多
We investigate the ground-state properties of the Anderson single impurity model （finite Coulomb impurity repulsion） with the Coupled Cluster Method. We consider different CCM reference states and approximation sche...We investigate the ground-state properties of the Anderson single impurity model （finite Coulomb impurity repulsion） with the Coupled Cluster Method. We consider different CCM reference states and approximation schemes and make comparison with exact Green＇s function results for the non-interacting model and with Brillouin-Wigner perturbation theory for the full interacting model. Our results show that coupled cluster techniques are well suited to quantum impurity problems.展开更多
The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one conne...The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one connected Wilson loop. We study the excited state energy and wavefunction in (2+1)-D SU(3) LGT up to the third order. The glueball mass shows a good scaling behavior.展开更多
Methane hydrates(MHs)play important roles in the fields of chemistry,energy,environmental sciences,etc.In this work,we employ the generalized energy-based fragmentation(GEBF)approach to compute the binding energies an...Methane hydrates(MHs)play important roles in the fields of chemistry,energy,environmental sciences,etc.In this work,we employ the generalized energy-based fragmentation(GEBF)approach to compute the binding energies and Raman spectra of various MH clusters.For the GEBF binding energies of various MH clusters,we first evaluated the various functionals of density functional theory(DFT),and compared them with the results of explicitly correlated combined coupled-cluster singles and doubles with noniterative triples corrections[CCSD(T)(F12^(*))]method.Our results show that the two best functionals are B3PW91-D3 and B97D,with mean absolute errors of only 0.27 and 0.47 kcal/mol,respectively.Then we employed GEBF-B3PW91-D3 to obtain the structures and Raman spectra of MH clusters with mono-and double-cages.Our results show that the B3PW91-D3 functional can well reproduce the experimental C-H stretching Raman spectra of methane in MH crystals,with errors less than 3 cm^(-1).As the size of the water cages increased,the C-H stretching Raman spectra exhibited a redshift,which is also in agreement with the experimental“loose cage-tight cage”model.In addition,the Raman spectra are only slightly affected by the neighboring environment(cages)of methane.The blueshifts of C-H stretching frequencies are no larger than 3 cm^(-1) for CH_(4) from monocages to doublecages.The Raman spectra of the MH clusters could be combined with the experimental Raman spectra to investigate the structures of methane hydrates in the ocean bottom or in the interior of interstellar icy bodies.Based on the B3PW91-D3 or B97D functional and machine learning models,molecular dynamics simulations could be applied to the nucleation and growth mechanisms,and the phase transitions of methane hydrates.展开更多
Electric quadrupole moments of low-lying excited states of Yb^+are calculated by relativistic coupled-cluster theory with perturbations from external fields.The field-dependent energy differentiation provides accurate...Electric quadrupole moments of low-lying excited states of Yb^+are calculated by relativistic coupled-cluster theory with perturbations from external fields.The field-dependent energy differentiation provides accurate values of the electric quadrupole moments of^2P3/2,^2D3/2,5/2,and^2F5/2,7/2 states which agree well with experimental values.The important role of the electronic correlation to the electric quadrupole moments is investigated.Our calculations indicate the early dispute of the electric quadrupole moment of the Yb^+(2F7/2)state for which the measured and theoretical values have a large discrepancy.These electric quadrupole moment values can help us to determine the electric quadrupole shifts in start-of-the-art experiments of the Yb+ion.展开更多
基金Supported by the Start-Up Funds of Xi’an Polytechnic University under Grant No BS1211the Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant No 2013JK0679
文摘Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg2 are studied by the coupled cluster theory with spin-orbit coupling. Spin-orbit coupling is included in the post Hartree-Fock procedure, i.e., in the coupled- cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg2.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874179,11447194,11574114,and 11874177)the Natural Science Foundation of Jilin Province,China(Grant No.20180101289JC)
文摘The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q, 5, or 6), complete basis set extrapolation functions with two-parameters and three-parameters, together with considering the contributions due to the core-valence electron correlation, scalar relativistic effects, spin–orbit coupling, and zero-point vibrational corrections. Our calculations show that both the neutral S_3 and anion S_3^- have open forms with C_(2r) vsymmetry. On the basis of the stable geometries, the adiabatic electron affinity of S_3 is determined to be 19041(11) cm^(-1), which is in excellent agreement with the experimental data(19059(7) cm^(-1)). The dependence of geometries and electron affinity on the computation level and physical corrections is discussed. The present computational results are helpful to the experimental molecular spectroscopy and bonding of S_3.
文摘We investigate the ground-state properties of the Anderson single impurity model （finite Coulomb impurity repulsion） with the Coupled Cluster Method. We consider different CCM reference states and approximation schemes and make comparison with exact Green＇s function results for the non-interacting model and with Brillouin-Wigner perturbation theory for the full interacting model. Our results show that coupled cluster techniques are well suited to quantum impurity problems.
文摘The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one connected Wilson loop. We study the excited state energy and wavefunction in (2+1)-D SU(3) LGT up to the third order. The glueball mass shows a good scaling behavior.
基金supported by the National Natural Science Foundation of China(No.22033004,No.21833002,No.21873046,and No.22073043)the Natural Science Foundation of Jiangsu Province(No.BK20210175)。
文摘Methane hydrates(MHs)play important roles in the fields of chemistry,energy,environmental sciences,etc.In this work,we employ the generalized energy-based fragmentation(GEBF)approach to compute the binding energies and Raman spectra of various MH clusters.For the GEBF binding energies of various MH clusters,we first evaluated the various functionals of density functional theory(DFT),and compared them with the results of explicitly correlated combined coupled-cluster singles and doubles with noniterative triples corrections[CCSD(T)(F12^(*))]method.Our results show that the two best functionals are B3PW91-D3 and B97D,with mean absolute errors of only 0.27 and 0.47 kcal/mol,respectively.Then we employed GEBF-B3PW91-D3 to obtain the structures and Raman spectra of MH clusters with mono-and double-cages.Our results show that the B3PW91-D3 functional can well reproduce the experimental C-H stretching Raman spectra of methane in MH crystals,with errors less than 3 cm^(-1).As the size of the water cages increased,the C-H stretching Raman spectra exhibited a redshift,which is also in agreement with the experimental“loose cage-tight cage”model.In addition,the Raman spectra are only slightly affected by the neighboring environment(cages)of methane.The blueshifts of C-H stretching frequencies are no larger than 3 cm^(-1) for CH_(4) from monocages to doublecages.The Raman spectra of the MH clusters could be combined with the experimental Raman spectra to investigate the structures of methane hydrates in the ocean bottom or in the interior of interstellar icy bodies.Based on the B3PW91-D3 or B97D functional and machine learning models,molecular dynamics simulations could be applied to the nucleation and growth mechanisms,and the phase transitions of methane hydrates.
基金Project supported by the National Natural Science Foundation of China(Grant No.11874064)the Strategic Priority and the Research Program of the Chinese Academy of Sciences(Grant No.XDB21030300)+3 种基金the National Key Research and Development Program of China(Grant No.2016YFA0302104)Yong Liu acknowledges the Project of Hebei Educational Department,China(Grant No.ZD2018015)the Natural Science Foundation of Hebei Province,China(Grant No.A2019203507)Bing-Bing Suo acknowledges the financial support from the National Natural Science foundation of China(Grant Nos.21673174 and 21873077).
文摘Electric quadrupole moments of low-lying excited states of Yb^+are calculated by relativistic coupled-cluster theory with perturbations from external fields.The field-dependent energy differentiation provides accurate values of the electric quadrupole moments of^2P3/2,^2D3/2,5/2,and^2F5/2,7/2 states which agree well with experimental values.The important role of the electronic correlation to the electric quadrupole moments is investigated.Our calculations indicate the early dispute of the electric quadrupole moment of the Yb^+(2F7/2)state for which the measured and theoretical values have a large discrepancy.These electric quadrupole moment values can help us to determine the electric quadrupole shifts in start-of-the-art experiments of the Yb+ion.
