Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction...Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.展开更多
Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbo...Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)_3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105. 0 kJ/mol and 39. 17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.展开更多
Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu...Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu）. The theoretical tensile strengths are calculated to be 25.3 GPa, 5.9 GPa, and 37.6 GPa for the fcc Cu single crystal in the [001], [110], and [111] directions, respectively. Among the three directions, the [110] direction is the weakest one due to the occurrence of structure transition at the lower strain and the weakest interaction of atoms between the （110） planes, while the [111] direction is the strongest direction because of the strongest interaction of atoms between the （111） planes. In terms of the elastic constants of Cu single crystal, we also estimate some mechanical quantities of polycrystalline Cu, including bulk modulus B, shear modulus G, Young＇s modulus Ep, and Poisson＇s ratio ~.展开更多
Presents the ab initio calculations performed for different symmetry groups of neutral molecular N 2 dimer, and the calculation of ground state and low lying singlet excited states for each symmetry group and conclude...Presents the ab initio calculations performed for different symmetry groups of neutral molecular N 2 dimer, and the calculation of ground state and low lying singlet excited states for each symmetry group and concludes from the results that there is an electric dipole transition between X 1A g and a 1B 3u (singlet singlet) excited states belonging to D 2h group symmetry, and discusses the vibrational energy levels and emission spectra calculates for this transition.展开更多
On the basis of the-improved self-exchange model of reorganization phenomenon and accurate potential functions from ab initio calculation at HFSCF 6-31G* and DZP levels a new calculation method was,presented for the i...On the basis of the-improved self-exchange model of reorganization phenomenon and accurate potential functions from ab initio calculation at HFSCF 6-31G* and DZP levels a new calculation method was,presented for the inner-sphere reorganization energy, values for diatomic molecular redox couples in gas phase electron transfer process have been calculated. Results agree well with the experimental data, and the effectiveness and importance of this method have been demonstrated for calculation of inner-sphere reorganization energy in gas phase electron transfer process.展开更多
Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augment...Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.展开更多
The marriage of artificial intelligence(AI)and Materials Genome Initiative(MGI)could profoundly change the landscape of modern materials research,leading to a new paradigm of data-driven and AI-driven materials discov...The marriage of artificial intelligence(AI)and Materials Genome Initiative(MGI)could profoundly change the landscape of modern materials research,leading to a new paradigm of data-driven and AI-driven materials discovery.In this perspective,we will give an overview on the central role of AI in the MGI research.In particular,an emerging research field of ab initio AI,which applies state-of-the-art AI techniques to help solve bottleneck problems of ab initio computation,will be introduced.The development of ab initio AI will greatly accelerate highthroughput computation,promote the construction of large materials database,and open new opportunities for future research of MGI.展开更多
A new potential energy surface （PES） for the atmospheric formation of sulfuric acid from OH＋SO2 is investigated using density functional theory and high-level ab initio molecular orbital theory. A pathway focused o...A new potential energy surface （PES） for the atmospheric formation of sulfuric acid from OH＋SO2 is investigated using density functional theory and high-level ab initio molecular orbital theory. A pathway focused on the new PES assumes the reaction to take place between the radical complex SO3.HO2 and H2O. The unusual stability of SO3.HO2 is the principal basis of the new pathway, which has the same final outcome as the current reaction mechanism in the literature but it avoids the production and complete release of SO3. The entire reaction pathway is composed of three consecutive elementary steps： （1） HOSO2＋O2-＋SO3.HO2, （2） SO3.HO2＋H20-＋SO3·H2O·HO2, （3） SO3.H20.HO2-＋H2SO4＋HO2. All three steps have small energy barriers, under 10 kcal/rnol, and are exotherrnic, and the new pathway is there- fore favorable both kinetically and therrnodynarnically. As a key step of the reactions, step （3）, HO2 serves as a bridge molecule for low-barrier hydrogen transfer in the hydrolysis of SO3. Two significant atmospheric implications are expected frorn the present study. First, SO3 is not released from the oxidation of SO2 by OH radical in the atmosphere. Second, the conversion of SO2 into sulfuric acid is weakly dependent on the humidity of air.展开更多
This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radia- tion Facility, the topological shape of ligand-free bovine serum albumin in solution has been investiga...This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radia- tion Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2~=t=0.25 ~_ （11=0.1 nm） which is co- incident with other ones＇ results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed.展开更多
The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory （MBPT）, the first work of which can be traced to Brown and Kuo＇s first attempt in 1966, derived from the Hama...The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory （MBPT）, the first work of which can be traced to Brown and Kuo＇s first attempt in 1966, derived from the Hamada-Johnstou nucleon-nucleon potential. However, the convergence of the MBPT is still unclear. On the other hand, ab initio theories, such as Green＇s function Monte Carlo （GFMC）, no-core shell model （NCSM）, and coupled-cluster theory with single and double excitations （CCSD）, have made many progress in recent years. However, due to the increasing demanding of computing resources, these ab initio applications are usually limited to nuclei with mass up to A = 16. Recently, people have realized the ab initio construction of valence-space effective interactions, which is obtained through a second-time renormalization, or to be more exactly, projecting the full-many- body Hamiltonian into core, one-body, and two-body cluster parts. In this paper, we present the investigation of such ab initio shell-model interactions, by the recent derived sd-shell effective interactions based on effective J-matrix Inverse Scattering Potential （JISP） and chiral effective-field theory （EFT） through NCSM. In this work, we have seen the similarity between the ab initio shell- model interactions and the interactions obtained by MBPT or by empirical fitting. Without the inclusion of three-body （3-bd） force, the ab initio shell-model interactions still share similar defects with the microscopic interactions by MBPT, i.e., T = 1 channel is more attractive while T = 0 channel is more repulsive than empirical interactions. The progress to include more many-body correlations and 3-bd force is still badly needed, to see whether such efforts of ab initio shell-model interactions can reach similar precision as the interactions fitted to experimental data.展开更多
The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optim...The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.展开更多
The electronic and molecular structures of the monomer and dimer of trimethylaluminium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C...The electronic and molecular structures of the monomer and dimer of trimethylaluminium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C3h symmetry, whew that of the dimer [Al(CH3)3]2 contains a carbon-bridged four-membered ring structure with C2h symmetry. The hydrogen-bridged six-membered ring structure is found to be unstable. The calculated dimerization energy for the four-membered ring structure is 78 kJ/mol, in close proximity to the experimental due of 85.27 kJ/mol.展开更多
The dibutyltin 3,4-dimethoxybenzotate compound {[（3,4-（CH3O）2C6H3COO） Sn（Bu-n）2]2O}2 has been synthesized by the reaction of dibutyltin oxide with 3,4-dimethoxybenzoic acid. Its structure was determined by X-ray...The dibutyltin 3,4-dimethoxybenzotate compound {[（3,4-（CH3O）2C6H3COO） Sn（Bu-n）2]2O}2 has been synthesized by the reaction of dibutyltin oxide with 3,4-dimethoxybenzoic acid. Its structure was determined by X-ray single-crystal diffraction. The crystal belongs to the triclinic system,space group P1 with a = 1.2003（2）,b = 1.2821（3）,c = 1.3666（3） nm,α = 80.50（3）,β = 65.56（3）,γ = 73.36（3）°,Z = 2,V = 1.8318（6） nm3,Dc = 1.530 Mg·m-3,μ（MoKa） = 1.413 mm-1,F（000） = 860,R = 0.0554 and wR = 0.1092. In the complex,each tin atom adopts a distorted tigonal bipyramidal structure,and the dimer structure is shaped by one Sn2O2 planar four-membered ring. The stabilities of the title complex,along with its orbital energies and composition characteristics of some frontier molecular orbitals have been investigated by means of quantum chemistry calculation methods.展开更多
Ab initio molecular method is used to theoretically investigate the interactions of waterwith the Cu(100)and Al(111)surface.Cu,,Al,and Al,dusters are used to simulate the differ-ent kinds of surfaces.At different basi...Ab initio molecular method is used to theoretically investigate the interactions of waterwith the Cu(100)and Al(111)surface.Cu,,Al,and Al,dusters are used to simulate the differ-ent kinds of surfaces.At different basis set level of H_O in adsorption system,the potential ener-gy surface of the HOH plane tilted of three systems are calculated.Without consideration of thed orbitals of the oxygen atom,the optimized structure is the water plane normal to the surface.and the H,O tilting of 40°~50°is found to require small amount of energy.When the dorbitals of oxygen atom are taken into account,the calculated structure of adsorbed H,Omonomer with an indined molecular axis such as Cu 50°,Al 40°is in an agreement with exper-imental resuits.The results indicate that the d orbitals of oxygen atom have the critical effed onthe structure of the adsorbed H2O monomer.展开更多
A novel organotin hydration dibenzyltin dichloride has been synthesized and its crystal structure was determined by X-ray diffraction. The crystal belongs to monoclinic, space group Pc with a = 1.1918（5）, b = 0.6199...A novel organotin hydration dibenzyltin dichloride has been synthesized and its crystal structure was determined by X-ray diffraction. The crystal belongs to monoclinic, space group Pc with a = 1.1918（5）, b = 0.6199（2）, c = 1.1074（5）nm, β = 106.899（7）°, V= 0.7828（8）nm3, Z = 2, Dc = 1.654 g/cm3,μ（MoKa） = 19.59 cm^-1, F（000） = 384, R = 0.0564 and RwR = 0.1427. The Sn-C bonds are 0.2140（9） and 0.2152（5） nm, Sn-Cl are 0.2385（4） and 0.2497（3） nm, and Sn-O is 0.2388（7） nm. The tin atom is five-coordinated in a distorted trigonal bipyramidal configuration. The study on the title complex has been performed with quantum chemistry calculation by means of G98W package on the Lanl2dz basis set. The stability of the complex as well as the orbital energies and composition characteristics of some frontier molecular orbitals has been investigated.展开更多
e have studied the electronic structures of dimeric diboroxane and aldiminob-orane by nieans of STO-3G .ib iuitio SCF method. The energies and the componentanalysis of niolecular orbitals near to frontier orbital hav...e have studied the electronic structures of dimeric diboroxane and aldiminob-orane by nieans of STO-3G .ib iuitio SCF method. The energies and the componentanalysis of niolecular orbitals near to frontier orbital have been given. By bothKoopman' s theoreni and △E_(scf)mietliod we have calculated the ionization potentialsof 8 higlier occupied orbitals and discussed the electron relaxation effect on IP' s cal-culations and the charge distribuuons for the two molecules.展开更多
Ab initio method has been employed to investigate the hydrogenbond between two HNCO molecules. Two types of hydrogen-bondings in HNCO dimers have been found, one type is N-H…O, the other is N-H…N. The latter is a li...Ab initio method has been employed to investigate the hydrogenbond between two HNCO molecules. Two types of hydrogen-bondings in HNCO dimers have been found, one type is N-H…O, the other is N-H…N. The latter is a little stabler than that of the former. The stabilization energies of the two types of dimers are estimated to be 13KJ/mol-21KJ/mol.展开更多
A new method is presented for approximate ab initio calculations in quantum chemistry. It is called CCAM (charge conserving approximation method). The calculation method does not include the use of empirical parameter...A new method is presented for approximate ab initio calculations in quantum chemistry. It is called CCAM (charge conserving approximation method). The calculation method does not include the use of empirical parameters. We use Slater type orbitals as basis set, replacing STO's by STO-2G functions to evaluate three- and four-center integrals and making the STO-2G two- orbital charge distributions have the same total charge as STO. The results are presented for test calculations on five molecules. In view of these results, CCAM is better than ab initio calculations over STO-6G in the results on total energies, kinetic energies and occupied orbital energies. In atomic populations, dipole moments and unoccupied orbital energies, CCAM is also satisfactory. We estimate that CCAM would be as fast as ab initio calculations over STO-2G in evaluating molecular integrals.展开更多
The combinations of machine learning with ab initio methods have attracted much attention for their potential to resolve the accuracy-efficiency dilemma and facilitate calculations for large-scale systems.Recently,equ...The combinations of machine learning with ab initio methods have attracted much attention for their potential to resolve the accuracy-efficiency dilemma and facilitate calculations for large-scale systems.Recently,equivariant message passing neural networks(MPNNs)that explicitly incorporate symmetry constraints have demonstrated promise for interatomic potential and density functional theory(DFT)Hamiltonian predictions.However,the high-order tensors used to represent node and edge information are coupled through the Clebsch–Gordan tensor product,leading to steep increases in computational complexity and seriously hindering the performance of equivariant MPNNs.Here,we develop high-order tensor machine-learning Hamiltonian(Hot-Ham),an E(3)equivariant MPNN framework that combines two advanced technologies:local coordinate transformation and Gaunt tensor product to efficiently model DFT Hamiltonians.These two innovations significantly reduce the complexity of tensor products from O(L^(6))to O(L^(3))or O(L^(2)log^(2)L)for the max tensor order L,and enhance the performance of MPNNs.Benchmarks on several public datasets demonstrate its state-of-the-art accuracy with relatively few parameters,and applications to multilayer twisted moire systems,heterostructures,and allotropes showcase its generalization ability and high efficiency.Our Hot-Ham method provides a new perspective for developing efficient equivariant neural networks and would be a promising approach for investigating the electronic properties of large-scale materials systems.展开更多
Metal-stuffed B–C compounds with sodalite clathrate structure have captured increasing attention due to their predicted exceptional superconductivity above liquid nitrogen temperature at ambient pressure.However,by n...Metal-stuffed B–C compounds with sodalite clathrate structure have captured increasing attention due to their predicted exceptional superconductivity above liquid nitrogen temperature at ambient pressure.However,by neglecting the quantum lattice anharmonicity,the existing studiesmay result in an incomplete understanding of such a lightweight system.Here,using state-of-the-art ab initio methods incorporating quantum effects and machine learning potentials,we revisit the properties of a series of XYB_(6)C_(6)clathrates where X and Y are metals.Our findings show that ionic quantum and anharmonic effects can harden the E_(g)and E_(u)vibrational modes,enabling the dynamical stability of 15 materials previously considered unstable in the harmonic approximation,including materials with previously unreported (XY)^(1+)state,which is demonstrated here to be crucial to reach high critical temperatures.Further calculations based on the anisotropic Migdal-Eliashberg equation demonstrate that the T_(c)values for KRbB_(6)C_(6)and RbB_(3)C_(3)among these stabilized compounds are 102 and 115 Kat 0 and 15 GPa,respectively,both being higher than T_(c)of 92 K of KPbB_(6)C_(6)at the anharmonic level.These record-high T_(c)values,surpassing liquid nitrogen temperatures,emphasize the importance of anharmonic effects in stabilizing B-C clathrates with large electron-phonon coupling strength and advancing the search for high-T_(c)superconductivity at(near)ambient pressure.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52002318 and 22103061)。
文摘Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.
文摘Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)_3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105. 0 kJ/mol and 39. 17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51101135)
文摘Employing the ab initio total energy method based on the density functional theory with the generalized gradient approximation, we have systematically investigated the theoretical mechanical properties of copper （Cu）. The theoretical tensile strengths are calculated to be 25.3 GPa, 5.9 GPa, and 37.6 GPa for the fcc Cu single crystal in the [001], [110], and [111] directions, respectively. Among the three directions, the [110] direction is the weakest one due to the occurrence of structure transition at the lower strain and the weakest interaction of atoms between the （110） planes, while the [111] direction is the strongest direction because of the strongest interaction of atoms between the （111） planes. In terms of the elastic constants of Cu single crystal, we also estimate some mechanical quantities of polycrystalline Cu, including bulk modulus B, shear modulus G, Young＇s modulus Ep, and Poisson＇s ratio ~.
文摘Presents the ab initio calculations performed for different symmetry groups of neutral molecular N 2 dimer, and the calculation of ground state and low lying singlet excited states for each symmetry group and concludes from the results that there is an electric dipole transition between X 1A g and a 1B 3u (singlet singlet) excited states belonging to D 2h group symmetry, and discusses the vibrational energy levels and emission spectra calculates for this transition.
文摘On the basis of the-improved self-exchange model of reorganization phenomenon and accurate potential functions from ab initio calculation at HFSCF 6-31G* and DZP levels a new calculation method was,presented for the inner-sphere reorganization energy, values for diatomic molecular redox couples in gas phase electron transfer process have been calculated. Results agree well with the experimental data, and the effectiveness and importance of this method have been demonstrated for calculation of inner-sphere reorganization energy in gas phase electron transfer process.
基金Supported by UGC,New Delhi through UGC-BSR(JRF)fellowships
文摘Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.
基金supported by the National Natural Science Foundation of China(grant no.12334003)the Basic Science Center Project of NSFC(grant no.52388201)+1 种基金the National Science Fund for Distinguished Young Scholars(grant no.12025405)the Beijing Advanced Innovation Center for Future Chip(ICFC),and the Beijing Advanced Innovation Center for Materials Genome Engineering.
文摘The marriage of artificial intelligence(AI)and Materials Genome Initiative(MGI)could profoundly change the landscape of modern materials research,leading to a new paradigm of data-driven and AI-driven materials discovery.In this perspective,we will give an overview on the central role of AI in the MGI research.In particular,an emerging research field of ab initio AI,which applies state-of-the-art AI techniques to help solve bottleneck problems of ab initio computation,will be introduced.The development of ab initio AI will greatly accelerate highthroughput computation,promote the construction of large materials database,and open new opportunities for future research of MGI.
基金partially funded by National Science Foundation of the United States(No.1012994)by California State University,Fullerton
文摘A new potential energy surface （PES） for the atmospheric formation of sulfuric acid from OH＋SO2 is investigated using density functional theory and high-level ab initio molecular orbital theory. A pathway focused on the new PES assumes the reaction to take place between the radical complex SO3.HO2 and H2O. The unusual stability of SO3.HO2 is the principal basis of the new pathway, which has the same final outcome as the current reaction mechanism in the literature but it avoids the production and complete release of SO3. The entire reaction pathway is composed of three consecutive elementary steps： （1） HOSO2＋O2-＋SO3.HO2, （2） SO3.HO2＋H20-＋SO3·H2O·HO2, （3） SO3.H20.HO2-＋H2SO4＋HO2. All three steps have small energy barriers, under 10 kcal/rnol, and are exotherrnic, and the new pathway is there- fore favorable both kinetically and therrnodynarnically. As a key step of the reactions, step （3）, HO2 serves as a bridge molecule for low-barrier hydrogen transfer in the hydrolysis of SO3. Two significant atmospheric implications are expected frorn the present study. First, SO3 is not released from the oxidation of SO2 by OH radical in the atmosphere. Second, the conversion of SO2 into sulfuric acid is weakly dependent on the humidity of air.
基金Project supported by the Chinese Academy of Science Innovation Key Project (Grant No KJCX2-SW-N06)
文摘This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radia- tion Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2~=t=0.25 ~_ （11=0.1 nm） which is co- incident with other ones＇ results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11505056, 11547312, 11547104, 11275067, 11275068, 11375062 and 11447109)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory （MBPT）, the first work of which can be traced to Brown and Kuo＇s first attempt in 1966, derived from the Hamada-Johnstou nucleon-nucleon potential. However, the convergence of the MBPT is still unclear. On the other hand, ab initio theories, such as Green＇s function Monte Carlo （GFMC）, no-core shell model （NCSM）, and coupled-cluster theory with single and double excitations （CCSD）, have made many progress in recent years. However, due to the increasing demanding of computing resources, these ab initio applications are usually limited to nuclei with mass up to A = 16. Recently, people have realized the ab initio construction of valence-space effective interactions, which is obtained through a second-time renormalization, or to be more exactly, projecting the full-many- body Hamiltonian into core, one-body, and two-body cluster parts. In this paper, we present the investigation of such ab initio shell-model interactions, by the recent derived sd-shell effective interactions based on effective J-matrix Inverse Scattering Potential （JISP） and chiral effective-field theory （EFT） through NCSM. In this work, we have seen the similarity between the ab initio shell- model interactions and the interactions obtained by MBPT or by empirical fitting. Without the inclusion of three-body （3-bd） force, the ab initio shell-model interactions still share similar defects with the microscopic interactions by MBPT, i.e., T = 1 channel is more attractive while T = 0 channel is more repulsive than empirical interactions. The progress to include more many-body correlations and 3-bd force is still badly needed, to see whether such efforts of ab initio shell-model interactions can reach similar precision as the interactions fitted to experimental data.
基金the Young Teachers' Foundation of Beijing University of Chemical Technology (Grant No. QN0018).
文摘The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.
基金Project supported by the National Natural Science Foundation of China.
文摘The electronic and molecular structures of the monomer and dimer of trimethylaluminium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C3h symmetry, whew that of the dimer [Al(CH3)3]2 contains a carbon-bridged four-membered ring structure with C2h symmetry. The hydrogen-bridged six-membered ring structure is found to be unstable. The calculated dimerization energy for the four-membered ring structure is 78 kJ/mol, in close proximity to the experimental due of 85.27 kJ/mol.
基金Project supported by the Key Foundation of Education Committee of Hunan Province (10A014,10K010)Key Subject Foundation of Hunan Province and SRTP Foundation of Hunan Province
文摘The dibutyltin 3,4-dimethoxybenzotate compound {[（3,4-（CH3O）2C6H3COO） Sn（Bu-n）2]2O}2 has been synthesized by the reaction of dibutyltin oxide with 3,4-dimethoxybenzoic acid. Its structure was determined by X-ray single-crystal diffraction. The crystal belongs to the triclinic system,space group P1 with a = 1.2003（2）,b = 1.2821（3）,c = 1.3666（3） nm,α = 80.50（3）,β = 65.56（3）,γ = 73.36（3）°,Z = 2,V = 1.8318（6） nm3,Dc = 1.530 Mg·m-3,μ（MoKa） = 1.413 mm-1,F（000） = 860,R = 0.0554 and wR = 0.1092. In the complex,each tin atom adopts a distorted tigonal bipyramidal structure,and the dimer structure is shaped by one Sn2O2 planar four-membered ring. The stabilities of the title complex,along with its orbital energies and composition characteristics of some frontier molecular orbitals have been investigated by means of quantum chemistry calculation methods.
文摘Ab initio molecular method is used to theoretically investigate the interactions of waterwith the Cu(100)and Al(111)surface.Cu,,Al,and Al,dusters are used to simulate the differ-ent kinds of surfaces.At different basis set level of H_O in adsorption system,the potential ener-gy surface of the HOH plane tilted of three systems are calculated.Without consideration of thed orbitals of the oxygen atom,the optimized structure is the water plane normal to the surface.and the H,O tilting of 40°~50°is found to require small amount of energy.When the dorbitals of oxygen atom are taken into account,the calculated structure of adsorbed H,Omonomer with an indined molecular axis such as Cu 50°,Al 40°is in an agreement with exper-imental resuits.The results indicate that the d orbitals of oxygen atom have the critical effed onthe structure of the adsorbed H2O monomer.
基金supported by the Key Fund of Education Committee of Hunan Province (06009)Natural Science Fundation of Hunan Province (05JJ40015, 06JJ50022)+1 种基金Science and Technology Fund of Hunan Province (2007FJ4140)Key Subject Fund and Key Lab Fund of Hunan Province
文摘A novel organotin hydration dibenzyltin dichloride has been synthesized and its crystal structure was determined by X-ray diffraction. The crystal belongs to monoclinic, space group Pc with a = 1.1918（5）, b = 0.6199（2）, c = 1.1074（5）nm, β = 106.899（7）°, V= 0.7828（8）nm3, Z = 2, Dc = 1.654 g/cm3,μ（MoKa） = 19.59 cm^-1, F（000） = 384, R = 0.0564 and RwR = 0.1427. The Sn-C bonds are 0.2140（9） and 0.2152（5） nm, Sn-Cl are 0.2385（4） and 0.2497（3） nm, and Sn-O is 0.2388（7） nm. The tin atom is five-coordinated in a distorted trigonal bipyramidal configuration. The study on the title complex has been performed with quantum chemistry calculation by means of G98W package on the Lanl2dz basis set. The stability of the complex as well as the orbital energies and composition characteristics of some frontier molecular orbitals has been investigated.
文摘e have studied the electronic structures of dimeric diboroxane and aldiminob-orane by nieans of STO-3G .ib iuitio SCF method. The energies and the componentanalysis of niolecular orbitals near to frontier orbital have been given. By bothKoopman' s theoreni and △E_(scf)mietliod we have calculated the ionization potentialsof 8 higlier occupied orbitals and discussed the electron relaxation effect on IP' s cal-culations and the charge distribuuons for the two molecules.
文摘Ab initio method has been employed to investigate the hydrogenbond between two HNCO molecules. Two types of hydrogen-bondings in HNCO dimers have been found, one type is N-H…O, the other is N-H…N. The latter is a little stabler than that of the former. The stabilization energies of the two types of dimers are estimated to be 13KJ/mol-21KJ/mol.
文摘A new method is presented for approximate ab initio calculations in quantum chemistry. It is called CCAM (charge conserving approximation method). The calculation method does not include the use of empirical parameters. We use Slater type orbitals as basis set, replacing STO's by STO-2G functions to evaluate three- and four-center integrals and making the STO-2G two- orbital charge distributions have the same total charge as STO. The results are presented for test calculations on five molecules. In view of these results, CCAM is better than ab initio calculations over STO-6G in the results on total energies, kinetic energies and occupied orbital energies. In atomic populations, dipole moments and unoccupied orbital energies, CCAM is also satisfactory. We estimate that CCAM would be as fast as ab initio calculations over STO-2G in evaluating molecular integrals.
基金supported by the National Natural Science Foundation of China(Grant Nos.12125404,T2495231,and 123B2049)the Basic Research Program of Jiangsu(Grant Nos.BK20233001,BK20241253,and BK20253009)+3 种基金the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant Nos.2024ZB002 and 2024ZB075)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20240695)the AI&AI for Science program of Nanjing University,the Artificial Intelligence and Quantum physics(AIQ)program of Nanjing Universitythe Fundamental Research Funds for the Central Universities。
文摘The combinations of machine learning with ab initio methods have attracted much attention for their potential to resolve the accuracy-efficiency dilemma and facilitate calculations for large-scale systems.Recently,equivariant message passing neural networks(MPNNs)that explicitly incorporate symmetry constraints have demonstrated promise for interatomic potential and density functional theory(DFT)Hamiltonian predictions.However,the high-order tensors used to represent node and edge information are coupled through the Clebsch–Gordan tensor product,leading to steep increases in computational complexity and seriously hindering the performance of equivariant MPNNs.Here,we develop high-order tensor machine-learning Hamiltonian(Hot-Ham),an E(3)equivariant MPNN framework that combines two advanced technologies:local coordinate transformation and Gaunt tensor product to efficiently model DFT Hamiltonians.These two innovations significantly reduce the complexity of tensor products from O(L^(6))to O(L^(3))or O(L^(2)log^(2)L)for the max tensor order L,and enhance the performance of MPNNs.Benchmarks on several public datasets demonstrate its state-of-the-art accuracy with relatively few parameters,and applications to multilayer twisted moire systems,heterostructures,and allotropes showcase its generalization ability and high efficiency.Our Hot-Ham method provides a new perspective for developing efficient equivariant neural networks and would be a promising approach for investigating the electronic properties of large-scale materials systems.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12374008, 12022408, 12304013, 12374009, 12074138, 22131006, 52288102, and 52090024)the Interdisciplinary Integration and Innovation Project of JLU, Fundamental Research Funds for the Central Universities and the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT), open project from state key laboratory of superhard materials (No. 202408)+6 种基金College Student Innovation and Entrepreneurship Training Program (No. S202310183153)support from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (Grant Agreement No. 802533)the Spanish Ministry of Science and Innovation (Grant No. PID2022142861NA-I00)the Department of Education, Universities and Research of the Eusko Jaurlaritza and the University of the Basque Country UPV/EHU (Grant No. IT1527-22)Simons Foundation through the Collaboration on New Frontiers in Superconductivity (Grant No. SFI-MPS-NFS-00006741-10)Y.-W.F. acknowledges the Extraordinary Grant of CSIC (No. 2025ICT122)the IKUR Strategy-High Performance Computing and Artificial Intelligence (HPC&AI) 2025-2026 of the Department of Science, Universities and Innovation of the Basque Government. Technical and human support provided by DIPC Supercomputing Center is gratefully acknowledged.
文摘Metal-stuffed B–C compounds with sodalite clathrate structure have captured increasing attention due to their predicted exceptional superconductivity above liquid nitrogen temperature at ambient pressure.However,by neglecting the quantum lattice anharmonicity,the existing studiesmay result in an incomplete understanding of such a lightweight system.Here,using state-of-the-art ab initio methods incorporating quantum effects and machine learning potentials,we revisit the properties of a series of XYB_(6)C_(6)clathrates where X and Y are metals.Our findings show that ionic quantum and anharmonic effects can harden the E_(g)and E_(u)vibrational modes,enabling the dynamical stability of 15 materials previously considered unstable in the harmonic approximation,including materials with previously unreported (XY)^(1+)state,which is demonstrated here to be crucial to reach high critical temperatures.Further calculations based on the anisotropic Migdal-Eliashberg equation demonstrate that the T_(c)values for KRbB_(6)C_(6)and RbB_(3)C_(3)among these stabilized compounds are 102 and 115 Kat 0 and 15 GPa,respectively,both being higher than T_(c)of 92 K of KPbB_(6)C_(6)at the anharmonic level.These record-high T_(c)values,surpassing liquid nitrogen temperatures,emphasize the importance of anharmonic effects in stabilizing B-C clathrates with large electron-phonon coupling strength and advancing the search for high-T_(c)superconductivity at(near)ambient pressure.
