Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (11): 2709-2716.doi: 10.3866/PKU.WHXB201609132

• ARTICLE • Previous Articles     Next Articles

An Improvement of the SAM Dispersion Correction in the APF-D Density Functional Method for Studying Intermolecular Interactions

Yu HE1,2,Yi-Bo WANG1,2,*()   

  1. 1 Key Laboratory of High Performance Computational Chemistry, Guiyang 550025, P. R. China
    2 Network and Information Center of Guizhou University, Guiyang 550025, P. R. China
  • Received:2016-07-11 Published:2016-11-08
  • Contact: Yi-Bo WANG E-mail:ybw@gzu.edu.cn
  • Supported by:
    the Natural Science Foundation of Guizhou Province, China(20082116)

Abstract:

Austin-Petersson-Frisch (APF) is a new hybrid density functional method that combines B3PW91 and PBE0. APF-D provides an additional empirical dispersion correction method based on a spherical atom model (SAM), which is different from the Grimme's empirical dispersion correction method. APF-D accurately describes the binding energy and the potential energy surfaces of complexes of noble gas atoms and small hydrocarbon dimers. However, APF-D is not accepted as a standard method to study intermolecular interactions because the results often show a large deviation from the normal range when using the APF-D method to calculate the binding energy of hydrogen bonded complexes, C-H…π and ππ interactions. Our research identified that such a deviation arises from some long-range dispersion that has been double counted by the APF function and the SAM dispersion correction. Therefore, we propose an improved APF-D method, termed APF-D*. By taking advantage of ζ, which is independent of SAM dispersion, we were able to solve effectively the problem of excessive dispersion compensation in APF-D. By comparing the results from S66 and L7 benchmark sets, we find that APF-D* greatly improved the precision of calculations over the traditional APF-D method. The overall accuracy of APF-D* was found to be comparable to or better than current leading DFT methods, such as B3LYP-D3 and ωB97X-D. However, both B3LYP-D3 and ωB97X-D have a much larger computational cost than APF-D*. We believe that APF-D* is a better method to calculate of the intermolecular energy of large molecules.

Key words: DFT-D, APF functional, SAM dispersion correction

MSC2000: 

  • O641