The effects of higher orders of perturbation theory on the correlation energy of atoms and bonds in molecules

Author(s)

Vincent, Mark A. ^{[1, 2]} ; Silva, Arnaldo F. ^{[1, 2]} ; McDonagh, James L. ^{[1, 2]} ; Popelier, Paul L. A. ^{[1, 2]}

Affiliation

^[1] Univ Manchester, Manchester Inst Biotechnol, 131 Princess St, Manchester M1 7DN, Lancs - England

^[2] Univ Manchester, Sch Chem, Oxford Rd, Manchester M13 9PL, Lancs - England

• Document type: Journal article
• Source: International Journal of Quantum Chemistry; v. 118, n. 8 APR 15 2018.
• Web of Science Citations: 7

Abstract

We examine, for the first time, the effects of higher orders of MOller-Plesset perturbation theory on the individual atoms within a molecule and the bonds between them, via the topological energy partitioning method of interacting quantum atoms. In real terms (i.e., not by absolute value) MP3 decreases the correlation energy of a bond, and MP4SDQ also decreases the energy of the atoms at either end of the bond. In addition, we investigated long-range through-space dispersive effects on a H-2 oligomer. Overall, MP3 is the largest correction to the correlation energy, and most of that energy is allocated to chemical bonds, reducing their values in actual terms. The MP4SDQ bond correlation correction, despite being relatively small, tends to have two effects: (i) for small or negative correlation energies MP4SDQ tends to decrease the bond correlation values even more, and (ii) for large (positive) bond correlation energies MP4SDQ tends to restore the bond correlation energies from the MP3 back toward the MP2 values. Furthermore, each individual part of a molecule or complex (atom or bond) has a specific convergence pattern for the MPn series: through-space interactions converge at MP2 but bonds converge at MP3 level. The atomic correlation energy appears to head toward convergence at the MP4 level. (AU)

• FAPESP's process: 14/21241-9 - The inclusion of polarization effects in the description of amino acids and peptides through the use of atomic multipoles obtained from electron densities
• Grantee: Arnaldo Fernandes da Silva Filho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/22247-3 - Using the Quantum Chemical Topology theory for modeling force fields for peptides using electron densities
• Grantee: Arnaldo Fernandes da Silva Filho
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor