Grid-based energy density analysis (EDA), in which numerical integration is performed for two-electron integrals by the pseudospectral method (Imamura et al., J. Chem. Phys. 2007, 126, 034103), is extended to correlated methods: second-order Møller-Plesset (MP2) perturbation and coupled-cluster singles and doubles (CCSD). Using EDA for MP2 and CCSD, we estimate atomic correlation energy differences and correlation energy density difference maps for C2H4-CH4 complexes. The analyses confirm that polarization and diffuse functions essentially contribute to the descriptions of weak interaction around the nuclei and in the area between C2H4 and CH4, respectively.
- CH-CH complex
- Coupled-cluster theory
- Energy density analysis
- Second-order Møller-Plesset perturbation theory
- Van der Waals interaction
ASJC Scopus subject areas
- Safety, Risk, Reliability and Quality