English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Vibrational heat-bath configuration interaction (VHCI) -- a selectedconfiguration interaction technique for vibrational structure theory -- hasrecently been developed in two independent works [J. Chem. Phys. 154, 074104(2021); Mol. Phys. 119, e1936250 (2021)], where it was shown to provideaccuracy on par with the most accurate vibrational structure methods with a lowcomputational cost. Here, we eliminate the memory bottleneck of thesecond-order perturbation theory (PT2) correction using the same(semi)stochastic approach developed previously for electronic structure theory.This allows us to treat, in an unbiased manner, much larger perturbativespaces, which are necessary for high accuracy in large systems. Stochasticerrors are easily controlled to be less than 1 cm$^{-1}$. We also report twoother developments: (i) we propose a new heat-bath criterion and an associatedexact implicit sorting algorithm for potential energy surfaces expressible as asum of products of one-dimensional potentials; (ii) we formulate VHCI to use avibrational self-consistent field (VSCF) reference, as opposed to the harmonicoscillator reference configuration used in previous reports. Interestingly, wefind that with VSCF, the minor improvements to the accuracy are outweighed bythe much higher computational cost associated with the loss of sparsity in theHamiltonian and integrals transformations needed for matrix element evaluation.

Vibrational heat-bath configuration interaction with semistochastic perturbation theory using harmonic oscillator or VSCF modals