物理化学学报 >> 1998, Vol. 14 >> Issue (09): 856-864.doi: 10.3866/PKU.WHXB19980917

研究简报 上一篇    

含芯电子相关能修正的G2理论——G2(ful)

苏克和, 王育彬, 文振翼   

  1. 西北工业大学化工系,西安 710072|西北大学现代物理所,西安 710068
  • 收稿日期:1997-11-27 修回日期:1998-03-06 发布日期:1998-09-15
  • 通讯作者: 苏克和

Core Electronic Correlation Modification of the Gaussian-2 Theory——G2(ful)

Su Ke-He, Wang Yu-Bin, Wen Zhen-Yi   

  1. Department of Chemical Engineering,Northwestern Polytechnical University,Xi'an,Shanxi 710072|Institute of Modern Physics,Northwest University,Xi'an,Shanxi 710068
  • Received:1997-11-27 Revised:1998-03-06 Published:1998-09-15
  • Contact: Su Ke-He

关键词: G2理论, 芯电子相关能, G2(ful)理论

Abstract:

A general method in considering the core electronic correlation energies has been proposed and introduced into the standard Gaussian-2 (G2)[7] theory by small post-Hartree-Fock calculations. In this paper an additional MP2(FC)/6-31G(d) calculation over the G2 procedures is employed and examined in modification in modification to the flaw of Frozen-Core (FC) approximation of G2 vai eq.:
ΔE(full)= E[MP2(full)/6-31G(d)]-E[MP2(FC)/6-31G(d)]
where the MP2(full)/6-31G(d) energy has been obtained in the molecular geometry optimizations. This energy, ΔE(full), is directly added into the total G2 energy of a molecule in facilitating the effect of core electronic correlations for each molecule in chemical reactions. It has been shown that the over-all average absolute deviation for the 125 reaction energies of the G2 test set (test set 1) is slightly reduced from 5.09 to 5.01 kJ, mol(-1) while for the 55 D0 values, which have been used for the derivation of the A coefficient of the empirical High-Level...更多-Correction (HLC), it is also reduced from 4.99 [for both G2 and G2(COMPLETE)[8]]to 4.77 kJ• mol(-1). In addition, larger errors (greater than ±8.4 kJ•mol(-1) for the D0 energies are improved, especially for the largest error of the D0 of SO2 This error is reduced from 21.3 to 15.4 kJ. mol(-1), in which the experimental geometry would further reduce it by 7.1kJ.mol(-1)[8]. Another improvement is the absolute value of the A coefficient in HLC being reduced from 4.81 for G2 to 4.34 milli-hartrees which is believed to be useful in isolating the relationship between the HLC and the FC approximation. Modifications to the original G2 from this work is denoted as G2(fu 1) and thus the G2 (fu 1) total energy for a molecule is
E[G2(fu 1)]= E[G2]+Δ E(full)h
with a new ΔE[HLC] =-0.19α- 4.34nβ milli-hartree.

Key words: G2 theory, Core electronic correlation energy, G2(ful) theory