Various forms of multi-reference perturbation theory, including our recently suggested 'invariant' form are compared for some diatomic supermolecules. While the 'invariant' zeroth-order Hamiltonian is not the direct sum of the zeroth-order fragment Hamiltonians, the size consistency errors in the fi
On the performance of the open-shell perturbation theory
✍ Scribed by FeiWu Chen; MeiJu Wei; WenJian Liu
- Book ID
- 107349323
- Publisher
- SP Science China Press
- Year
- 2011
- Tongue
- English
- Weight
- 402 KB
- Volume
- 54
- Category
- Article
- ISSN
- 1674-7291
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📜 SIMILAR VOLUMES
A new open-shell perturbation theory is formulated in terms of symmetric spin orbitals. Only one set of spatial orbitals is required, thereby reducing the number of independent coeffmients in the perturbed wavefunctions. For second order, the computational cost is shown to be similar to a closed-she
A form of open shell perturbation theory that is invariant with respect to orbital degeneracy is proposed. This new methodology is based entirely on the spin-restricted formalism. Preliminary numerical results are presented and compared with other formulations of perturbation theory.
## Abstract All the second‐order density matrix spin components for the spin‐projected Slater determinant are presented as expansions in direct products of powers of unprojected spin‐ and residual electron density matrices. Spin components of the second‐order transition density matrices between spi