The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are invest...The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.展开更多
Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles. A linear dispersion relation and a Kortewe...Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles. A linear dispersion relation and a Korteweg-de Vries-Burgers equation governing the dust acoustic shock waves are obtained. The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically. The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.展开更多
We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance （NQR）, and zero-field nuclear magnetic resonance （NMR） measurements on single crystals of multiferroics CuBr2. High qual...We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance （NQR）, and zero-field nuclear magnetic resonance （NMR） measurements on single crystals of multiferroics CuBr2. High quality of the sample is demonstrated by the sharp magnetic and magnetic-driven ferroelectric transition at TN = TC≈74 K. The zero-field 79Br and 81Br NMR are resolved below TN. The spin-lattice relaxation rates reveal charge fluctuations when cooled below 60 K. Evidences of an increase of NMR linewidth, a reduction of dielectric constant, and an increase of magnetic susceptibility are also seen at low temperatures. These data suggest an emergent instability which competes with the spiral magnetic ordering and the ferroelectricity. Candidate mechanisms are discussed based on the quasi-one-dimensional nature of the magnetic system.展开更多
Using the perturbation method, the modified variable coefficient Kadomtsev- Petviashvili （MKP） equation governing nonlinear （lust acoustic solitary waves is for the first time derived with the combined effects of a...Using the perturbation method, the modified variable coefficient Kadomtsev- Petviashvili （MKP） equation governing nonlinear （lust acoustic solitary waves is for the first time derived with the combined effects of adiabatic dust charge fluctuation and higher-order transverse perturbation in inhomogeneous dusty plasmas due to the spatial gradients of dust charge and plasma densities. The MKP equation is reduced to the standard Kadomtsev-Petviashvili （KP） equation. The numerical results show that inhomogeneity has strong influence on the nonlinear properties of dust acoustic solitary waves.展开更多
The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory serve...The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.展开更多
Charge-dependent correlations from both background and charge separation contribute to experimental observables in heavy-ion collisions.In this paper,we use stochastic hydrodynamics to study background charge asymmetr...Charge-dependent correlations from both background and charge separation contribute to experimental observables in heavy-ion collisions.In this paper,we use stochastic hydrodynamics to study background charge asymmetry due to fluctuations.Using the rapidity-dependent correlation and a simple ansatz for particle distributions,we find a fluctuation-induced correlation to provide a type of background F-correlation.Experimental data for Au+Au collisions at(sNN)1/2=200 GeV are compared.We also make predictions for F-correlations in isobar collisions.Combining this with our previous chiral magnetic effect results,we obtainδ-correlations for collisions in the three types of system.Computations from our model show an almost identical background with less than 2%difference for isobars,but roughly 10%difference for their charge separations.In combination with our earlier works,we provide a consistent method of calculating both the chiral magnetic effect and the charged background in the context of stochastic hydrodynamics.展开更多
Dynamic charge transfers,or charge flux oscillations,generated by anharmonic phonon coupling,have attracted increasing interest in cuprate superconductors.In this article,a new computational method is developed to ana...Dynamic charge transfers,or charge flux oscillations,generated by anharmonic phonon coupling,have attracted increasing interest in cuprate superconductors.In this article,a new computational method is developed to analyze such charge fluxes along all atomic bonds for a given material,which unveils a surprising fact that cupratematerials with high superconducting transition temperature show a strong tendency to support global charge flux flows beyond local charge oscillations.Such fluxes further show a strong correlation with both the maximum superconducting transition temperature of different cuprate families and the strong magnetic fluctuations as well.Motivated by these findings,we construct a charge flux model derived from quantum field theory to evaluate the effective interactions mediated by these flux flows.Finally,we discuss the implications of this flux-driven pairing mechanism for the design of new high-T_(c) superconductors,offering a potential strategy for discovering higher T_(c) superconductive materials.展开更多
The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P va...The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ωc, which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma of P<<1, when the charging frequency Ωc is much smaller than the dusty plasma frequency wd, there is a strong charge density fluctuation which is of character of dust acoustic eigen wave. For a dusty plasma of P>>1, when the frequency Ωc, is much larger than wd there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.展开更多
The infinite-layer cuprate ACu O_(2)(A=Ca,Sr,Ba)possesses the simplest crystal structure among numerous cuprate superconductors and can serve as a prototypical system to explore the unconventional superconductivity.Ba...The infinite-layer cuprate ACu O_(2)(A=Ca,Sr,Ba)possesses the simplest crystal structure among numerous cuprate superconductors and can serve as a prototypical system to explore the unconventional superconductivity.Based on the first-principles electronic structure calculations,we have studied the electronic and magnetic properties of the infinite-layer cuprate SrCuO_(2)from a phonon perspective.We find that interesting fluctuations of charges,electrical dipoles,and local magnetic moments can be induced by the atomic displacements of phonon modes in SrCuO_(2)upon the hole doping.Among all optical phonon modes of SrCuO_(2)in the antiferromagnetic Néel state,only the A_(1g)mode that involves the full-breathing O vibrations along the Cu-O bonds can cause significant fluctuations of local magnetic moments on O atoms and dramatic charge redistributions between Cu and O atoms.Notably,due to the atomic displacements of the A_(1g)mode,both the charge fluctuations on Cu and the electrical dipoles on O show a dome-like evolution with increasing hole doping,quite similar to the experimentally observed behavior of the superconducting T_(c);in comparison,the fluctuations of local magnetic moments on O display a monotonic enhancement along with the hole doping.Further analyses indicate that around the optimal doping,there exists a large softening in the frequency of the A_(1g)phonon mode and a van Hove singularity in the electronic structure close to the Fermi level,suggesting potential electron-phonon coupling.Our work reveals the important role of the full-breathing O phonon mode playing in the infinite-layer SrCuO_(2),which may provide new insights in understanding the cuprate superconductivity.展开更多
The new signature of liquid-gas phase transition has been well indicated by the higher-order fluctuations of the largest fragment charge,but the uncertainties of critical temperatures based on this signature have not ...The new signature of liquid-gas phase transition has been well indicated by the higher-order fluctuations of the largest fragment charge,but the uncertainties of critical temperatures based on this signature have not been revealed.This study extracts the critical temperatures of liquid-gas phase transition in nuclear reactions and investigates their uncertainties.Utilizing the isospin-dependent quantum molecular dynamics model in conjunction with the statistical model GEMINI enables us to describe the dynamical path from the initial to the final state.An isotope thermometer and a quantum fluctuation thermometer are employed to extract the nuclear temperature.The higher-order fluctuations of the largest fragment charge and critical temperatures are studied in^(124)Sn+^(120)Sn collisions ranging from 400 to 1000 MeV/nucleon and^(124)Sn+AZ collisions at 600 MeV/nucleon.Observations revealed that the pseudo-critical point is robustly indicated by the higher-order fluctuations of the largest fragment charge.The critical temperatures extracted by the isotope thermometer are relatively consistent,with an uncertainty of 15%,while those obtained by the quantum fluctuation thermometer are heavily influenced by the incident energy and mass number of target nuclei.The excitation energy E∗and bound charge Zbound are used for event-sorting.These two ensembles represent the statistical properties of the initial and final states of the system,respectively.The initial-final correlations of statistical properties might lead to two phenomena.First,the size distribution of the largest fragment at the pseudo-critical point based on the Zbound ensemble is wide,while that based on E∗ensemble exhibits bimodality,which is a typical characteristic in the liquid-gas coexistence of a finite system.Second,the temperature at the pseudo-critical point based on the Zbound ensemble is higher than that based on the E∗ensemble.Furthermore,the projectile-like system exhibits a significant dynamical effect in its evolution path from the initial to final state,closely associated with the fluctuation of critical temperature.展开更多
The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners s...The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners significant attention for its unique properties,including an unconventional charge density wave(CDW)and superconductivity(SC)[2],as well as the interplay between CDW and SC[3].展开更多
The electrostatic potential caused by a test-charge particle in a positive dust-electron plasma is studied, accounting for the d^Lst-charge fluctuations associated with ultraviolet photoelectron and thermionic emissio...The electrostatic potential caused by a test-charge particle in a positive dust-electron plasma is studied, accounting for the d^Lst-charge fluctuations associated with ultraviolet photoelectron and thermionic emissions. For this purpose, the set of Vlasov-Poisson equations coupled with the dust charging equation is solved by using the space-time Fourier transform technique. As a consequence, a modified dielectric response function is obtained for dust-acoustic waves in a positive dust-electron plasma. By imposing certain conditions on the velocity of the test charge, the electrostatic potential is decomposed into the Deby^Hiickel （DH）, wake-field （WF）, and far-field （FF） potentials that are significantly modified in the limit of a large dust-charge relaxation rate both analytically and numerically. The results can be helpful for understanding dust crystallization/coagulation in two- component plasmas, where positively charged dust grains are present.展开更多
The microscopic mechanisms of ion hydration and ion selectivity in biomolecular systems are long-standing research topics, in which the difficulty is how to reasonably and accurately describe the ion-water and ion-bio...The microscopic mechanisms of ion hydration and ion selectivity in biomolecular systems are long-standing research topics, in which the difficulty is how to reasonably and accurately describe the ion-water and ion-biomolecule interactions. This paper summarizes the development and applications of the atom-bond electronegativity equalization fluctuating charge force field model, ABEEM/MM, in the investigations of ion hydration, metalloproteins and ion-DNA bases systems. Based on high-level quantum chemistry calculations, the parameters were optimized and the molecular potential functions were constructed and applied to studies of structures, activities, energetics, and thermodynamic and kinetic properties of these ion-containing sys- tems. The results show that the performance of ABEEM]MM is generally better than that of the common force fields, and its accuracy can reach or approach that of the hlgh-level ab initio MP2 method. These studies provide a solid basis for further investigations of ion selectivity in biomolecular systems, the structures and properties of metalloproteins and other related ion-containing systems.展开更多
We demonstrate the effects of electron-electron （e-e） interactions in monolayer graphene quantum capacitors. Ultrathin yttrium oxide showed excellent per-formance as the dielectric layer in top-gate device geometry....We demonstrate the effects of electron-electron （e-e） interactions in monolayer graphene quantum capacitors. Ultrathin yttrium oxide showed excellent per-formance as the dielectric layer in top-gate device geometry. The structure and dielectric constant of the yttrium oxide layers have been carefully studied. The inverse compressibility retrieved from the quantum capacitance agreed fairly well with the theoretical predictions for the e--e interactions in monolayer graphene at different temperatures. We found that electron-hole puddles played a significant role in the low-density carrier region in graphene. By considering the temperature-dependent charge fluctuation, we established a model to explain the round-off effect originating from the e-e interactions in monolayer graphene near the Dirac point.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10475066 and 10347006）.
文摘The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.
基金supported by the National Natural Science Foundation of China(Grant No.10975114)the Prominent Youth Foundation of Lanzhou University of Technology,China(Grant No.0910ZXC082)
文摘Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles. A linear dispersion relation and a Korteweg-de Vries-Burgers equation governing the dust acoustic shock waves are obtained. The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically. The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.
基金Project supported by the Ministry of Science and Technology of China(Grant No.2016YFA0300504)the National Natural Science Foundation of China(Grant No.11374364)+1 种基金the Fundamental Research Funds for the Central Universities of Chinathe Research Funds of Renmin University,China(Grant No.14XNLF08)
文摘We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance （NQR）, and zero-field nuclear magnetic resonance （NMR） measurements on single crystals of multiferroics CuBr2. High quality of the sample is demonstrated by the sharp magnetic and magnetic-driven ferroelectric transition at TN = TC≈74 K. The zero-field 79Br and 81Br NMR are resolved below TN. The spin-lattice relaxation rates reveal charge fluctuations when cooled below 60 K. Evidences of an increase of NMR linewidth, a reduction of dielectric constant, and an increase of magnetic susceptibility are also seen at low temperatures. These data suggest an emergent instability which competes with the spiral magnetic ordering and the ferroelectricity. Candidate mechanisms are discussed based on the quasi-one-dimensional nature of the magnetic system.
基金supported by National Natural Science Foundation of China (No. 10975114)the Science-Technology Foundation of Gansu Province(1014RJZA017)the Prominent Youth Foundation of LUT (No. 0910ZXC082)
文摘Using the perturbation method, the modified variable coefficient Kadomtsev- Petviashvili （MKP） equation governing nonlinear （lust acoustic solitary waves is for the first time derived with the combined effects of adiabatic dust charge fluctuation and higher-order transverse perturbation in inhomogeneous dusty plasmas due to the spatial gradients of dust charge and plasma densities. The MKP equation is reduced to the standard Kadomtsev-Petviashvili （KP） equation. The numerical results show that inhomogeneity has strong influence on the nonlinear properties of dust acoustic solitary waves.
文摘The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.
文摘Charge-dependent correlations from both background and charge separation contribute to experimental observables in heavy-ion collisions.In this paper,we use stochastic hydrodynamics to study background charge asymmetry due to fluctuations.Using the rapidity-dependent correlation and a simple ansatz for particle distributions,we find a fluctuation-induced correlation to provide a type of background F-correlation.Experimental data for Au+Au collisions at(sNN)1/2=200 GeV are compared.We also make predictions for F-correlations in isobar collisions.Combining this with our previous chiral magnetic effect results,we obtainδ-correlations for collisions in the three types of system.Computations from our model show an almost identical background with less than 2%difference for isobars,but roughly 10%difference for their charge separations.In combination with our earlier works,we provide a consistent method of calculating both the chiral magnetic effect and the charged background in the context of stochastic hydrodynamics.
文摘Dynamic charge transfers,or charge flux oscillations,generated by anharmonic phonon coupling,have attracted increasing interest in cuprate superconductors.In this article,a new computational method is developed to analyze such charge fluxes along all atomic bonds for a given material,which unveils a surprising fact that cupratematerials with high superconducting transition temperature show a strong tendency to support global charge flux flows beyond local charge oscillations.Such fluxes further show a strong correlation with both the maximum superconducting transition temperature of different cuprate families and the strong magnetic fluctuations as well.Motivated by these findings,we construct a charge flux model derived from quantum field theory to evaluate the effective interactions mediated by these flux flows.Finally,we discuss the implications of this flux-driven pairing mechanism for the design of new high-T_(c) superconductors,offering a potential strategy for discovering higher T_(c) superconductive materials.
文摘The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ωc, which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma of P<<1, when the charging frequency Ωc is much smaller than the dusty plasma frequency wd, there is a strong charge density fluctuation which is of character of dust acoustic eigen wave. For a dusty plasma of P>>1, when the frequency Ωc, is much larger than wd there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1403103,and 2019YFA0308603)the Beijing Natural Science Foundation(Grant No.Z200005)+2 种基金the National Natural Science Foundation of China(Grant Nos.12174443,and 11934020)supported by the National Key R&D Program of China(Grant No.2017YFA0302903)supported by the Project funded by China Postdoctoral Science Foundation(Grant No.2022M723355)。
文摘The infinite-layer cuprate ACu O_(2)(A=Ca,Sr,Ba)possesses the simplest crystal structure among numerous cuprate superconductors and can serve as a prototypical system to explore the unconventional superconductivity.Based on the first-principles electronic structure calculations,we have studied the electronic and magnetic properties of the infinite-layer cuprate SrCuO_(2)from a phonon perspective.We find that interesting fluctuations of charges,electrical dipoles,and local magnetic moments can be induced by the atomic displacements of phonon modes in SrCuO_(2)upon the hole doping.Among all optical phonon modes of SrCuO_(2)in the antiferromagnetic Néel state,only the A_(1g)mode that involves the full-breathing O vibrations along the Cu-O bonds can cause significant fluctuations of local magnetic moments on O atoms and dramatic charge redistributions between Cu and O atoms.Notably,due to the atomic displacements of the A_(1g)mode,both the charge fluctuations on Cu and the electrical dipoles on O show a dome-like evolution with increasing hole doping,quite similar to the experimentally observed behavior of the superconducting T_(c);in comparison,the fluctuations of local magnetic moments on O display a monotonic enhancement along with the hole doping.Further analyses indicate that around the optimal doping,there exists a large softening in the frequency of the A_(1g)phonon mode and a van Hove singularity in the electronic structure close to the Fermi level,suggesting potential electron-phonon coupling.Our work reveals the important role of the full-breathing O phonon mode playing in the infinite-layer SrCuO_(2),which may provide new insights in understanding the cuprate superconductivity.
基金Supported by the National Natural Science Foundation of China (11875328, 12075327)the Key Laboratory of Nuclear Data foundation (JCKY2022201C157)the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (22lgqb39)。
文摘The new signature of liquid-gas phase transition has been well indicated by the higher-order fluctuations of the largest fragment charge,but the uncertainties of critical temperatures based on this signature have not been revealed.This study extracts the critical temperatures of liquid-gas phase transition in nuclear reactions and investigates their uncertainties.Utilizing the isospin-dependent quantum molecular dynamics model in conjunction with the statistical model GEMINI enables us to describe the dynamical path from the initial to the final state.An isotope thermometer and a quantum fluctuation thermometer are employed to extract the nuclear temperature.The higher-order fluctuations of the largest fragment charge and critical temperatures are studied in^(124)Sn+^(120)Sn collisions ranging from 400 to 1000 MeV/nucleon and^(124)Sn+AZ collisions at 600 MeV/nucleon.Observations revealed that the pseudo-critical point is robustly indicated by the higher-order fluctuations of the largest fragment charge.The critical temperatures extracted by the isotope thermometer are relatively consistent,with an uncertainty of 15%,while those obtained by the quantum fluctuation thermometer are heavily influenced by the incident energy and mass number of target nuclei.The excitation energy E∗and bound charge Zbound are used for event-sorting.These two ensembles represent the statistical properties of the initial and final states of the system,respectively.The initial-final correlations of statistical properties might lead to two phenomena.First,the size distribution of the largest fragment at the pseudo-critical point based on the Zbound ensemble is wide,while that based on E∗ensemble exhibits bimodality,which is a typical characteristic in the liquid-gas coexistence of a finite system.Second,the temperature at the pseudo-critical point based on the Zbound ensemble is higher than that based on the E∗ensemble.Furthermore,the projectile-like system exhibits a significant dynamical effect in its evolution path from the initial to final state,closely associated with the fluctuation of critical temperature.
基金support from the National Key R&D Program of China(2021YFA1401800 and 2021YFA1400202)the National Natural Science Foundation of China(12141404)+7 种基金the Natural Science Foundation of Shanghai(22ZR1479700 and 23XD1422200)Shaofeng Duan acknowledged support from the China Postdoctoral Science Foundation(2022M722108)the China National Postdoctoral Program for Innovative Talents(BX20230216)the National Natural Science Foundation of China(12304178)Yanfeng Guo acknowledged the National Key R&D Program of China(2023YFA1406100)the Double First-Class Initiative Fund of ShanghaiTech Universitysupport from the National Key R&D Program of China(2022YFA1402400 and 2021YFA1400100)the National Natural Science Foundation of China(12074248).
文摘The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners significant attention for its unique properties,including an unconventional charge density wave(CDW)and superconductivity(SC)[2],as well as the interplay between CDW and SC[3].
文摘The electrostatic potential caused by a test-charge particle in a positive dust-electron plasma is studied, accounting for the d^Lst-charge fluctuations associated with ultraviolet photoelectron and thermionic emissions. For this purpose, the set of Vlasov-Poisson equations coupled with the dust charging equation is solved by using the space-time Fourier transform technique. As a consequence, a modified dielectric response function is obtained for dust-acoustic waves in a positive dust-electron plasma. By imposing certain conditions on the velocity of the test charge, the electrostatic potential is decomposed into the Deby^Hiickel （DH）, wake-field （WF）, and far-field （FF） potentials that are significantly modified in the limit of a large dust-charge relaxation rate both analytically and numerically. The results can be helpful for understanding dust crystallization/coagulation in two- component plasmas, where positively charged dust grains are present.
基金supported by the National Natural Science Foundation of China(21133005 and 20703022)
文摘The microscopic mechanisms of ion hydration and ion selectivity in biomolecular systems are long-standing research topics, in which the difficulty is how to reasonably and accurately describe the ion-water and ion-biomolecule interactions. This paper summarizes the development and applications of the atom-bond electronegativity equalization fluctuating charge force field model, ABEEM/MM, in the investigations of ion hydration, metalloproteins and ion-DNA bases systems. Based on high-level quantum chemistry calculations, the parameters were optimized and the molecular potential functions were constructed and applied to studies of structures, activities, energetics, and thermodynamic and kinetic properties of these ion-containing sys- tems. The results show that the performance of ABEEM]MM is generally better than that of the common force fields, and its accuracy can reach or approach that of the hlgh-level ab initio MP2 method. These studies provide a solid basis for further investigations of ion selectivity in biomolecular systems, the structures and properties of metalloproteins and other related ion-containing systems.
文摘We demonstrate the effects of electron-electron （e-e） interactions in monolayer graphene quantum capacitors. Ultrathin yttrium oxide showed excellent per-formance as the dielectric layer in top-gate device geometry. The structure and dielectric constant of the yttrium oxide layers have been carefully studied. The inverse compressibility retrieved from the quantum capacitance agreed fairly well with the theoretical predictions for the e--e interactions in monolayer graphene at different temperatures. We found that electron-hole puddles played a significant role in the low-density carrier region in graphene. By considering the temperature-dependent charge fluctuation, we established a model to explain the round-off effect originating from the e-e interactions in monolayer graphene near the Dirac point.
