David Tew (University Oxford)

10:00 - 10:30

Abstract

David Tew

University Oxford

Many open-shell electronic states can be accurately represented using a single configuration state function. We examine Lindgren’s normal-ordered exponential ansatz to correlate specific spin states using spin-free excitation operators, with the aid of automatic equation generation software. We present an intermediately normalised and size-extensive reformulation of the unlinked working equations, and analyse the performance of the method with single and double excitations for simple molecular systems in terms of accuracy and size-consistency [1]. We furthermore discuss the challenges presented for treating multi-reference states where more than one configuration state function is important [2] and propose a perspective and an algorithm that would naturally leverage the power of a fault-tolerant quantum computer [3].

[1] A. Gunasekera, N. Lee, D. P. Tew, arxiv:2403.05389.

[2] D. Marti-Dafcik, N. Lee, H.  G. A. Burton, D. P. Tew, arxiv:2402.08858.

[3] D. Marti-Dafcik, H.  G. A. Burton, D. P. Tew, arxiv:2404.18878.