Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration interaction method with quantum-electrodynamics corrections performed by the GRASP code, we calculate the fine-s...Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration interaction method with quantum-electrodynamics corrections performed by the GRASP code, we calculate the fine-structure energy levels of the ground-state configuration （1s^22s^22p^3） of the nitrogen isoelectronic sequence, according to the L-S coupling scheme with atomic number Z up to 22. Based on the calculated results, we elucidate the mechanism of the orderings of fine-structure energy levels of 2^ D3/2,5/2 and 2^P1/2,3/2 respectively, i.e. for 2^D3/2,5/2 orderings, the competition between the spin-orbit interactions and the Breit interactions; for 2^P1/2,3/2 orderings, the electron correlations, especially the electron correlations owing to the 2p^5 configuration interactions.展开更多
The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momen...The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory （DFT）, and symmetry-adapted- cluster configuration-interaction （SAC-CI） methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.展开更多
The electronic structures of PF and PF＋ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, a...The electronic structures of PF and PF＋ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, and the Davidson correction（q-Q） are also considered. The spectroscopic parameters of bound states are derived by the electronic structures of PF and PF＋, which are in good accordance with the measurements. The transition dipole moments of spin-allowed transitions are evaluated, and the radiative lifetimes of several A S states of PF and PF＋ are obtained.展开更多
An unusual resonance feature of the photodetachment cross-section for the 3σu channel of F2- observed in the early static-exchange study is confirmed by using correlated target (F2) wavefunctions determined by config...An unusual resonance feature of the photodetachment cross-section for the 3σu channel of F2- observed in the early static-exchange study is confirmed by using correlated target (F2) wavefunctions determined by configuration interaction (CI). The magnitude of the cross-sections is lowered from that in earlier calculation by the potential of the correlated target.展开更多
A new algorithm for evaluating the coupling coefficients and the addresses of molecular integrals in configuration interaction (CI) calculations is presented, which leads to an improved CI calculation program CGUGA. T...A new algorithm for evaluating the coupling coefficients and the addresses of molecular integrals in configuration interaction (CI) calculations is presented, which leads to an improved CI calculation program CGUGA. The validity arid efficiency of the new code are compared with other programs, such as MELD and GAUSSIAN-94.展开更多
Various configuration-based multi-reference second order perturbation approaches were investigated and a new scheme averting intruder states was suggested. The codes based on these schemes were tested by example calcu...Various configuration-based multi-reference second order perturbation approaches were investigated and a new scheme averting intruder states was suggested. The codes based on these schemes were tested by example calculations.展开更多
An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we s...An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we study the 1s2s ^1S isoelectronic sequence from helium to neon, and compare with other methods. By taking into account the Eekart upper-bound theorem, we obtained more accurate and more intuitively understandable results than Hartree-Fock and multi-configuration Hartree-Fock reported results.展开更多
A new contracted CI scheme—adjustable contracted CI scheme—is presented and programed. The efficiency of this scheme is tested by some example calculations. The result shows that the application of the new scheme is...A new contracted CI scheme—adjustable contracted CI scheme—is presented and programed. The efficiency of this scheme is tested by some example calculations. The result shows that the application of the new scheme is flexible and the correlation energy loss is lower than that of the original externally contracted CI method. Keywords: configuration interaction, contracted CI method, correlation energy.展开更多
基金Supported by the Key Project of the Ministry of Education of China under Grant No 306020, the National Natural Science Foundation of China, the National High-Tech ICF Committee in China and the Yin-He Super-computer Center, Institute of Applied Physics and Mathematics, Beijing, China, and the National Basic Research Programme of China under Grant No 2006CB921408.
文摘Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration interaction method with quantum-electrodynamics corrections performed by the GRASP code, we calculate the fine-structure energy levels of the ground-state configuration （1s^22s^22p^3） of the nitrogen isoelectronic sequence, according to the L-S coupling scheme with atomic number Z up to 22. Based on the calculated results, we elucidate the mechanism of the orderings of fine-structure energy levels of 2^ D3/2,5/2 and 2^P1/2,3/2 respectively, i.e. for 2^D3/2,5/2 orderings, the competition between the spin-orbit interactions and the Breit interactions; for 2^P1/2,3/2 orderings, the electron correlations, especially the electron correlations owing to the 2p^5 configuration interactions.
基金supported by the National Natural Science Foundation of China(Grant No.11174175)the Tsinghua University Initiative Scientific Research Program,China
文摘The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory （DFT）, and symmetry-adapted- cluster configuration-interaction （SAC-CI） methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.
基金Supported by the National Natural Science Foundation of China under Grant No 11404180the Natural Science Foundation of Heilongjiang Province under Grant Nos F201335,A2015010,and A2015011the Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province under Grant No LBH-Q14159
文摘The electronic structures of PF and PF＋ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, and the Davidson correction（q-Q） are also considered. The spectroscopic parameters of bound states are derived by the electronic structures of PF and PF＋, which are in good accordance with the measurements. The transition dipole moments of spin-allowed transitions are evaluated, and the radiative lifetimes of several A S states of PF and PF＋ are obtained.
基金Project supported by the National Natural Science Foundation of China and the State Education Commission of china.
文摘An unusual resonance feature of the photodetachment cross-section for the 3σu channel of F2- observed in the early static-exchange study is confirmed by using correlated target (F2) wavefunctions determined by configuration interaction (CI). The magnitude of the cross-sections is lowered from that in earlier calculation by the potential of the correlated target.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29773035)
文摘A new algorithm for evaluating the coupling coefficients and the addresses of molecular integrals in configuration interaction (CI) calculations is presented, which leads to an improved CI calculation program CGUGA. The validity arid efficiency of the new code are compared with other programs, such as MELD and GAUSSIAN-94.
文摘Various configuration-based multi-reference second order perturbation approaches were investigated and a new scheme averting intruder states was suggested. The codes based on these schemes were tested by example calculations.
基金Project supported by the National Natural Science Foundation of China （Grant No 10347126）. Acknowledgements Xiong Zhuang acknowledges the Greek State Scholarship Foundation （I.K.Y.） and the National Hellenic Research Foundation Scholarship that partially supported this work.
文摘An analytic configuration interaction method based on variationally optimized internally orthogonalized modified Laguerre orbitals is presented. We have developed the corresponding computer code. For application, we study the 1s2s ^1S isoelectronic sequence from helium to neon, and compare with other methods. By taking into account the Eekart upper-bound theorem, we obtained more accurate and more intuitively understandable results than Hartree-Fock and multi-configuration Hartree-Fock reported results.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29773035).
文摘A new contracted CI scheme—adjustable contracted CI scheme—is presented and programed. The efficiency of this scheme is tested by some example calculations. The result shows that the application of the new scheme is flexible and the correlation energy loss is lower than that of the original externally contracted CI method. Keywords: configuration interaction, contracted CI method, correlation energy.
