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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The potential energy curve of the F$_2$ molecule is calculated withFixed-Node Diffusion Monte Carlo (FN-DMC) using Configuration Interaction(CI)-type trial wavefunctions. To keep the number of determinants reasonable(the first and second derivatives of the trial wavefunction need to becalculated at each step of FN-DMC), the CI expansion is restricted to thosedeterminants that contribute the most to the total energy. The selection of thedeterminants is made using the so-called CIPSI approach (ConfigurationInteraction using a Perturbative Selection made Iteratively). Quite remarkably,the nodes of CIPSI wavefunctions are found to be systematically improved whenincreasing the number of selected determinants. To reduce the non-parallelismerror of the potential energy curve a scheme based on the use of a$R$-dependent number of determinants is introduced. Numerical results show thatimproved FN-DMC energy curves for the F$_2$ molecule are obtained whenemploying CIPSI trial wavefunctions. Using the Dunning's cc-pVDZ basis set theFN-DMC energy curve is of a quality similar to that obtained with FCI/cc-pVQZ.A key advantage of using selected CI in FN-DMC is the possibility of improvingnodes in a systematic and automatic way without resorting to a preliminarymulti-parameter stochastic optimization of the trial wavefunction performed atthe Variational Monte Carlo level as usually done in FN-DMC.

Fixed-Node Diffusion Monte Carlo potential energy curve of the fluorine molecule F2 using selected configuration interaction trial wavefunctions