Subtractive manufacturing with geminal powers:making good use of a bad wave function

ABSTRACT

The cluster Jastrow antisymmetric geminal power ansatz was recently introduced as a promising approach for treating weak and strong electron correlations simultaneously. One crucial aspect of this ansatz is that the Jastrow operator allows the geminal power to achieve size consistency through the deletion of unphysical ionic terms. Here, we present data suggesting that the effects of such deletions go much deeper, causing the geminal to ‘intentionally’ take on a highly unphysical form that, in the presence of the Jastrow's deletions, nonetheless results in an accurate final wave function, a process that we note is similar to the variation-after-projection approach of projected Hartree–Fock theory. Indeed, in both LiF and N₂, we show that the optimal geminal is quite unphysical if considered on its own, but in ways that the Jastrow easily corrects to yield a highly accurate final wave function.

Keywords:

• Strong correlation
• geminals
• coupled cluster
• quantum Monte Carlo

Acknowledgements

This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The manuscript preparation and GAGP results were supported by the University of California.

Disclosure statement

No potential conflict of interest was reported by the author.