## Abstract A new perturbation approach is proposed that enhances the low‐order, perturbative convergence by modifying the zeroth‐order Hamiltonian in a manner that enlarges any small‐energy denominators that may otherwise appear in the perturbative expansion. This intruder state avoidance (ISA) me
Møller–Plesset theory for atomic ground state energies
✍ Scribed by J. S. Binkley; J. A. Pople
- Publisher
- John Wiley and Sons
- Year
- 1975
- Tongue
- English
- Weight
- 418 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0020-7608
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Mø–Plesset theory, in which electron correlation energy is calculated by perturbation techniques, is used in second order to calculate energies of the ground states of atoms up to neon. The unrestricted Hartree–Fock (UHF) Hamiltonian is used as the unperturbed system and the technique is then described as unrestricted Mø–Plesset to second order (UMP2). Use of large Gaussian basis sets suggests that the limiting UMP2 energies with a complete basis of s, p, and d functions account for 75–84% of the correlation energy. Preliminary estimates of the contributions of basis functions with higher angular quantum numbers indicate that full UMP2 limits give even more accurate total energies.
📜 SIMILAR VOLUMES
A state-selective (intermediate Hamiltonian) formulation of the recently proposed multi-partitioning M~ller-Plesset perturbation theory is presented. The novel approach offers the possibility to combine the decontracted treatment of the reference space parts of wavefunctions with numerical stability