Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reaching Full Correlation through Nonorthogonal Configuration
  Interaction: A Second-Order Perturbative Approach   Nonorthogonal multireference methods can predict statically correlated
adiabatic energies while providing chemical insight through the combination of
diabatic reference states. However, reaching quantitative accuracy using
nonorthogonal multireference expansions remains a significant challenge. In
this work, we present the first rigorous perturbative correction to
nonorthogonal configuration interaction, allowing the remaining dynamic
correlation to be reliably computed. Our second-order "NOCI-PT2" theory
exploits a zeroth-order generalised Fock Hamiltonian and builds the first-order
interacting space using single and double excitations from each reference
determinant. This approach therefore defines the rigorous nonorthogonal
extension to conventional multireference perturbation theory. We find that
NOCI-PT2 can quantitatively predict multireference potential energy surfaces
and provides state-specific ground and excited states for adiabatic avoided
crossings. Furthermore, we introduce an explicit imaginary-shift formalism
requiring shift values that are an order of magnitude smaller than those used
in conventional multireference perturbation theory.

14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg