物理化学学报 >> 1992, Vol. 8 >> Issue (03): 307-312.doi: 10.3866/PKU.WHXB19920306

研究论文 上一篇    下一篇

半正交化基近似计算的改进

丁涪江; 张良辅; 李广年   

  1. 中国科学院成都有机化学研究所,成都 610015
  • 收稿日期:1990-12-10 修回日期:1991-04-18 发布日期:1992-06-15
  • 通讯作者: 丁涪江

Improvement of Approximate Calculations Based on Semiorthogonalized Orbitals

Ding Fu-Jiang; Zhang Liang-Fu; Li Guang-Nian   

  1. Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610015
  • Received:1990-12-10 Revised:1991-04-18 Published:1992-06-15
  • Contact: Ding Fu-Jiang

摘要: Kashiwagi建议, 在量子化学从头计算中采用半正交化基组, 在电子排斥积分中忽略某些正交轨道间的重迭,同时保留核吸引积分中的类似重迭。本文建议在核吸引积分中也忽略这些微分重迭。这一改进提高了计算的精度。对仍然保留的微分重迭, 在计算三、四中心积分时建议在保持电荷守恒的条件下, 用较简单的轨道对之间的微分重迭代替, 大大节约了计算机时。

关键词: 近似从头算, 半正交化, 积分近似, 电荷守恒

Abstract: Kashiwagi used semiorthogonalized orbitals as basis set in quantum chemicalcal culations and proposed a scheme in which two-electron integrals containing orthogonalized orbital pairs were neglected, but the same kind of one-electron integrals were reserved. We proposed in this paper that one-electron integrals containing ortho-gonalized orbital pairs should be neglected too. This improvement makes the calcu-lations more accurate, because nuclear attractive energy is approximately equal to electron repulsive energy in a system. We use simpler orbitals to evaluate threeand four-center integrals, while keeping charge conservation. These two improvements can save a lot of computer time in approximate ab initio calculations.

Key words: Approximate calculation, Semiorthogonalized orbital, Integral approximation, Charge conservation