𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Size-consistent selected configuration interaction calculations. A few tests of efficiency

✍ Scribed by Àngels Povill; Rosa Caballol; Jaime Rubio; Jean Paul Malrieu

Publisher
Elsevier Science
Year
1993
Tongue
English
Weight
765 KB
Volume
209
Category
Article
ISSN
0009-2614

No coin nor oath required. For personal study only.

✦ Synopsis

As recently shown, size extensivily of any truncated or selected CI may be obtained by a self-consistent dressing of the determinant energies. This dressing has been implemented in two direct CI algorithms and its efficiency is illustrated on a series of eight-electron problems for which full-Cl results are known (HF, H20, NH, in DZP basis sets). The dressing has been applied to Cls defined by single and double excitations on complete active spaces, single and double substitutions on selected reference spaces or by iterative double threshold selection. In most cases the dressing reduces the error by at least a factor of two to three and in selected CIs it makes it possible to save about one order of magnitude in the size of the CI. The best results are obtained from iteratively selected CIs, the error being lower than 5 x IO-* hat-tree for 2 X IO' determinant CIs.

📜 SIMILAR VOLUMES

Multireference self-consistent size-cons
Multireference self-consistent size-consistent configuration interaction method. A few applications to ground and excited states
✍ J. Meller; J.P. Malrieu; J.L. Heully 📂 Article 📅 1995 🏛 Elsevier Science 🌐 English ⚖ 592 KB

The state-specific self-consistent dressing of a multireference C! matrix and a simplified scheme of MRCEPA(0) type are tested on a series of benchmark problems (H a, H20, CH~). The method is demonstrated to be strictly separable provided that the reference space is separable (i.e. it contains all p

A numerical test on the size consistency
A numerical test on the size consistency of some multireference configuration interaction approaches
✍ J. Rubio; A. Povill; F. Illas; J.P. Malrieu 📂 Article 📅 1992 🏛 Elsevier Science 🌐 English ⚖ 656 KB

The size consistency of selected multireference CI approaches is tested on two model problems, namely seven non-interacting H, molecules at their equilibrium bond length r, or at 2r, and seven non-interacting Ne atoms, In all cases the results obtained from the two-class CIPSI method (which is a mul