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spectroscopic parameters of X^3∑^-, a^1△, and A^＇3△ Electronic States of SO Radical

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Chinese Journal of Chemical Physics 2012年第5期25卷 533-539,I0003页

作者： Jie-min Wang Heng-qiang Feng Jin-feng Sun De-heng Shi Zun-lue Zhu Department of Physics and Electronic Information Luoyang Normal CollegeLuoyang 471022China College of Physics and Information Engineering Henan Normal UniversityXinxiang 453007China

The potential energy curves （PECs） of three low-lying electronic states （X^3∑, a^1△, and a^3△） of SO radical have been studied by ab initio quantum chemical method. The calcula- tions were carried out with the full valence complete active space self-consistent field method followed by the highly accurate valence internally contracted multireference configuration in- teraction （MRCI） approach in combination with correlation-consistent basis sets. Effects of the core-valence correlation and relativistic corrections on the PECs are taken into account. The core-valence correlation correction is carried out with the cc-pCVDZ basis set. The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian approximation, and the correction is performed at the level of cc-pV5Z basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification （MRCI＋Q）. These PECs are extrapolated to the complete basis set limit by the two-point energy extrapolation scheme. With these PECs, the spectroscopic parameters are determined.

关键词： spectroscopic parameter Core-valence correlation Relativistic correction Extrapolation

Elastic scattering of two H(~2S_g) and N(~4S_u) atoms at low temperatures and accurate spectroscopic parameters of NH (X^3Σ^-) radical

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Chinese Physics B 2008年第6期17卷 2090-2096页

作者：施德恒张金平孙金锋朱遵略刘玉芳杨向东 College of Physics & Electronic Engineering Xinyang Normal University College of Physics & Information Engineering Henan Normal University Institute of Atomic & Molecular Physics Sichuan University

This paper reports that the interaction potential for the X3Z- state of NH radical is constructed at the CCSD（T）/ cc-PV6Z level of theory. Using this potential, this paper calculates the spectroscopic parameters （De, Re, ωe, ωeχe, αe and Be） and their values are of 3.578eV, 0.10368nm, 3286.833cm^-1, 78.433cm^-1, 0.6469cm^-1 and 16.6735cm^-1 respectively, which are in excellent agreement with the experiments. Then the total of 14 vibrational states has been found when J=0 by solving the radial Schrodinger equation of nuclear motion. For each vibrational state, the vibrational manifolds are reported for the first time. And last, the total cross sections, s-wave, p-wave and d-wave cross sections are computed for the elastic collisions between two ground-state atoms （hydrogen and nitrogen） at low temperatures. It finds that the total elastic cross sections are dominated by s-wave scattering when the collision energy is below 10^-6a.u. The pronounced shape resonance is found at energy of 6.1 × 10^-6a.u. Calculations have shown that the shape resonance comes from the p-wave contributions.

关键词： atomic collision total elastic cross section shape resonance partial-wave cross section spectroscopic parameter

Theoretical investigations of spectroscopic parameters and molecular constants for electronic ground state of Cl_2 and its isotopes

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Chinese Physics B 2010年第10期19卷 236-244页

作者：施德恒张小妞刘慧朱遵略孙金锋 College of Physics & Electronic Engineering Xinyang Normal University College of Physics & Information Engineering Henan Normal University

The potential energy curve of the C12 （X1∑g＋） is investigated by the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in combination with the largest correlation-consistent basis set, aug-cc-pV6Z, in the valence range. The theoretical spectroscopic parameters and the molecular constants of three isotopes, 35Cl2, 35Cl37Cl and 37Cl2, are studied. For the 35Cl2（X1∑g＋）, the values of Do, De, Re, We, we）we, ae and Be are obtained to be 2.3921 eV, 2.4264 eV, 0.19939 nm, 555.13 cm-1, 2.6772 cm-1, 0.001481 cm-1 and 0.24225 cm-1, respectively. For the 356137Cl（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are calculated to be 2.3918 eV, 2.4257 eV, 0.19939 nm, 547.68 cm-1, 2.6234 cm-1, 0.00140 cm^1 and 0.23572 cm-1, respectively. And for the 37Cl2（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are obtained to be 2.3923 eV, 2.4257 eV, 0.19939 nm, 540.06 cm-1, 2.5556 cm-1, 0.00139 cm-1 and 0.22919 cm-1, respectively. These spectroscopic results are in good agreement with the available experimental data. With the potential of Cl2 molecule determined at the MRCI/aug-cc-pV6Z level of theory, the total of 59 vibrational states is predicted for each isotope when the rotational quantum number J equals zero （J = 0）. The theoretical vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0, which are in excellent accordance with the available experimental findings.

关键词： isotope effect spectroscopic parameter molecular constant vibrational level

Investigations on analytic potential energy function, spectroscopic parameters and vibrational manifolds (J = 0) of the SD + (X^3 Σ^- ) ion

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Chinese Physics B 2009年第2期18卷 558-564页

作者：张金平施德恒孙金锋刘玉芳朱遵略马恒 College of Physics & Electronic Engineering Xinyang Normal University College of Physics & Information Engineering Henan Normal University

This paper investigates the spectroscopic properties of the SD^＋（X^3∑^-） ion by employing the coupled-cluster singles-doubles-approximate-triples [CCSD（T）] theory combining with the quintuple correlation-consistent basis set augmented with diffuse functions （aug-cc-pV5Z） of Dunning and co-workers. The accurate adiabatic potential energy function is obtained by the least-squares fitting method with the 100 ab initio points, which are calculated at the unrestricted CCSD（T）/aug-cc-pV5Z level of theory over the internuclear separation range from 0.09 to 2.46 nm. Using the potential, it accurately determines the spectroscopic parameters （De, ωeХe, αe and Be）. The present De, Re, We, ωeХe, αe and Be results are of 3.69119 eV, 0.13644 nm, 1834.949 cm^-1, 25.6208 cm^-1, 0.1068 cm^-1 and 4.7778 cm^-1, respectively, which are in remarkably good agreement with the experimental findings. A total of 29 vibrational states has been predicted by numerically solving the radial Schrodinger equation of nuclear motion when the rotational quantum number J equals zero. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reported when J = 0 for the first time, which are in good accord with the measurements wherever available.

关键词： spectroscopic parameter vibrational level inertial rotation constant centrifugal distortion constant

Investigations of spectroscopic parameters and molecular constants for X^1Σ_g^+, w^3△_u, and W^1△_u electronic states of P_2 molecule

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Chinese Physics B 2012年第2期21卷 235-242页

作者： Wang Jie-Min Feng Heng-Qiang Sun Jin-Feng Shi De-Heng Department of Physics&Electronic Information Luoyang Normal CollegeLuoyang 471022China College of Physics&Information Engineering Henan Normal UniversityXinxiang 453007China

The potential energy curves （PECs） of three low-lying electronic states （X1 ∑g^＋, w^3 △u, and W1 △u） of P2 molecule are investigated using the full valence complete active space self-consistent field （CASSCF） method followed by the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in conjunction with the correlation-consistent basis set in the valence range. The PECs of the electronic states involved are modified by the Davidson correction and extrapolated to the complete basis set （CBS） limit. With these PECs, the spectroscopic parameters of the three electronic states are determined and compared in detail with the experimental data. The comparison shows that excellent agreement exists between the present results and the available experimental data. The complete vibrational states are computed for the W3Au and WlAu electronic states when the rotational quantum number J equals zero and the vibrational level G（v）, the inertial rotation constant By, and the centrifugal distortion constant Dv of the first 30 vibrational states are reported, which accord well with the experimental data. The present results show that the two-point extrapolation scheme can obviously improve the quality of spectroscopic parameters and molecular constants.

关键词： spectroscopic parameter molecular constant Davidson correction extrapolation

Study on spectroscopic parameters and molecular constants of HCl(X^1Σ^+) molecule by using multireference configuration interaction approach

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Chinese Physics B 2010年第5期19卷 224-232页

作者：张小妞施德恒张金平朱遵略孙金锋 College of Physics and Information Engineering Henan Normal University

Equilibrium internuclear separations, harmonic frequencies and potential energy curves （PECs） of HCI（X1∑＋） molecule are investigated by using the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in combination with a series of correlation-consistent basis sets in the valence range. The PECs are all fitted to the Murrell-Sorbie function, and they are used to accurately derive the spectroscopic parameters （De, Do, ωeXe, αe and Be） Compared with the available measurements, the PEC obtained at the basis set, aug-cc-pV5Z, is selected to investigate the vibrational manifolds. The constants Do, De, Re, We, ωeXe, Ore and Be at this basis set are 4.4006 eV, 4.5845 eV, 0.12757 rim, 2993.33 cm^-1, 52.6273 cm^-1, 0.2981 cm^-1 and 10.5841 cm^-1, respectively, which almost perfectly conform to the available experimental results. With the potential determined at the MRCI/aug-cc-pV5Z level of theory, by numerically solving the radial Schrodinger equation of nuclear motion in the adiabatic approximation, a total of 21 vibrational levels are predicted. Complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reproduced, which are in excellent agreement with the available Rydberg-Klein-Rees data. Most of these theoretical vibrational manifolds are reported for the first time to the best of our knowledge.

关键词： dissociation energy spectroscopic parameter vibrational level inertial rotation constant

Multireference configuration interaction study on spectroscopic properties of low-lying electronic states of As_2 molecule

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Chinese Physics B 2013年第9期22卷 358-365页

作者：王杰敏刘强 Department of Physics & Electronic Information Luoyang Normal College

The potential energy curves （PECs） of four electronic states （X^1∑g＋, e^3△u, a3∑^-u, and d3Лg） of an As2 molecule are investigated employing the complete active space self-consistent field （CASSCF） method followed by the valence internally contracted multireference configuration interaction （MRCI） approach in conjunction with the correlation-consistent aug-cc- pV5Z basis set. The effect on PECs by the relativistic correction is taken into account. The way to consider the relativistic correction is to employ the second-order Douglas-Kroll Hamiltonian approximation. The correction is made at the level of a cc-pVSZ basis set. The PECs of the electronic states involved are extrapolated to the complete basis set limit. With the PECs, the spectroscopic parameters （Te, Re, ωe, ωeXe, ωeye, ae, βe, γe, and Be） of these electronic states are determined and compared in detail with those reported in the literature. Excellent agreement is found between the present results and the experimental data. The first 40 vibrational states are studied for each electronic state when the rotational quantum number J equals zero. In addition, the vibrational levels, inertial rotation and centrifugal distortion constants of d3Hg electronic state are reported which are in excellent agreement with the available measurements. Comparison with the experimental data shows that the present results are both reliable and accurate.

关键词： spectroscopic parameter molecular constant relativistic correction extrapolation

Accurate spectroscopic constants of the lowest two electronic states in S_2 molecule with explicitly correlated method

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Chinese Physics B 2016年第1期25卷 543-548页

作者：魏长立张晓美丁大军闫冰 Institute of Atomic and Molecular Physics Jilin University

A computational scheme for accurate spectroscopic constants was presented in this work and applied to the lowest two electronic states of sulfur dimer. A high-level ab initio calculation utilizing explicitly correlated multireference con- figuration interaction method （MRCI-F12） was performed to compute the potential energy curves （PECs） of the ground triplet X3Eg and first excited singlet alAg states of sulfur dimer with cc-pCVXZ-F12（X = T, Q） basis sets. The effects of Davidson modification, core-valence correlation correction, and scalar relativistic correction on the spectroscopic con- stants were examined. The vibration-rotation spectra of the two electronic states were provided. Our computational results show excellent agreement with existing available experimental values, and the errors of main spectroscopic constants are within 0.1% order of magnitude. The present computational scheme is cheap and accurate, which is expected for extensive investigations on the potential energy curves or surfaces of other molecular systems.

关键词： sulfur dimer MRCI-F12 spectroscopic parameter core-valence correlation

The theoretical character of the X^1 Σ^+ and A^1 Σ^+ states of ScN

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Chinese Physics B 2009年第2期18卷 549-552页

作者：白凤娟杨传路钱琪张玲 College of Physics and Electronic Engineering Ludong University

This paper calculates the potential energy curves （PECs） of the ground state （X^1∑^＋） and excited state （A^1∑^＋） of SeN molecule by multireference configuration interaction method. The correct character of the PECs has been gripped while they had been improperly reported in the literature. Based on the PECs, the spectroscopic parameters and vibrational energy levels are determined, and compared with experimental data and other theoretical works available at the present.

关键词： potential energy curve spectroscopic parameter vibrational energy level multireference configuration interaction