Extension of selected configuration interaction for transcorrelated methods

A Ammar, A Scemama, E Giner - The Journal of Chemical Physics, 2022 - pubs.aip.org
In this work, we present an extension of popular selected configuration interaction (SCI)
algorithms to the Transcorrelated (TC) framework. Although we used in this work the recently …

Biorthonormal Orbital Optimization with a Cheap Core-Electron-Free Three-Body Correlation Factor for Quantum Monte Carlo and Transcorrelation

A Ammar, A Scemama, E Giner - Journal of Chemical Theory and …, 2023 - ACS Publications
We introduce a novel three-body correlation factor that is designed to vanish in the core
region around each nucleus and approach a universal two-body correlation factor for …

Nonunitary projective transcorrelation theory inspired by the f12 ansatz

SL Ten-No - The Journal of Chemical Physics, 2023 - pubs.aip.org
An alternative nonunitary transcorrelation, inspired by the F12 ansatz, is investigated. In
contrast to the Jastrow transcorrelation of Boys-Handy, the effective Hamiltonian of this …

TC++: First-principles calculation code for solids using the transcorrelated method

M Ochi - Computer Physics Communications, 2023 - Elsevier
TC++ is a free/libre open-source software of the transcorrelated (TC) method for first-
principles calculation of solids. Here, the TC method is one of the promising wave-function …

Sorting out quantum monte carlo

J Richter-Powell, L Thiede, A Asparu-Guzik… - arxiv preprint arxiv …, 2023 - arxiv.org
Molecular modeling at the quantum level requires choosing a parameterization of the
wavefunction that both respects the required particle symmetries, and is scalable to systems …

Toward Compact Selected Configuration Interaction Wave Functions with Quantum Monte Carlo─A Case Study of C2

J Ludovicy, R Dahl, A Luchow - Journal of Chemical Theory and …, 2023 - ACS Publications
The 1Σg+ ground state of C2 is investigated using truncated CIPSI-Jastrow CSF wave
functions with Hartree–Fock orbitals within the framework of variational and diffusion …

Transcorrelated selected configuration interaction in a bi-orthonormal basis and with a cheap three-body correlation factor

A Ammar, A Scemama, E Giner - The Journal of Chemical Physics, 2023 - pubs.aip.org
In this work, we develop a mathematical framework for a selected configuration interaction
(SCI) algorithm within a bi-orthogonal basis for transcorrelated (TC) calculations. The bi …

Beyond Single-Reference Fixed-Node Approximation in Ab Initio Diffusion Monte Carlo Using Antisymmetrized Geminal Power Applied to Systems with Hundreds of …

K Nakano, S Sorella, D Alfè, A Zen - Journal of Chemical Theory …, 2024 - ACS Publications
Diffusion Monte Carlo (DMC) is an exact technique to project out the ground state (GS) of a
Hamiltonian. Since the GS is always bosonic, in Fermionic systems, the projection needs to …

Compactification of Determinant Expansions via Transcorrelation

A Ammar, A Scemama, PF Loos, E Giner - arxiv preprint arxiv:2405.02640, 2024 - arxiv.org
Although selected configuration interaction (SCI) algorithms can tackle much larger Hilbert
spaces than the conventional full CI (FCI) method, the scaling of their computational cost …

Double excitation energies from quantum Monte Carlo using state-specific energy optimization

S Shepard, RL Panadés-Barrueta… - Journal of chemical …, 2022 - ACS Publications
We show that recently developed quantum Monte Carlo methods, which provide accurate
vertical transition energies for single excitations, also successfully treat double excitations …