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Title: Influence of pseudopotentials on excitation energies from selected configuration interaction and diffusion Monte Carlo

Abstract

Due to their diverse nature, the faithful description of excited states within electronic structure theory methods remains one of the grand challenges of modern theoretical chemistry. Quantum Monte Carlo (QMC) methods have been applied very successfully to ground state properties but still remain generally less effective than other non-stochastic methods for electronically excited states. Nonetheless, we have recently reported accurate excitation energies for small organic molecules at the fixed-node diffusion Monte Carlo (FN-DMC) within a Jastrow-free QMC protocol relying on a deterministic and systematic construction of nodal surfaces using the selected configuration interaction (sCI) algorithm known as CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively). Albeit highly accurate, these all-electron calculations are computationally expensive due to the presence of core electrons. One very popular approach to remove these chemically-inert electrons from the QMC simulation is to introduce pseudopotentials (also known as effective core potentials). Taking the water molecule as an example, we investigate the influence of Burkatzki-Filippi-Dolg (BFD) pseudopotentials and their associated basis sets on vertical excitation energies obtained with sCI and FN-DMC methods. Although these pseudopotentials are known to be relatively safe for ground state properties, we evidence that special care may be required if one strives formore » highly accurate vertical transition energies. Indeed, comparing all-electron and valence-only calculations, we show that using pseudopotentials with the associated basis sets can induce differences of the order of 0.05 eV on the excitation energies. Fortunately, a reasonable estimate of this shift can be estimated at the sCI level.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1529010
Alternate Identifier(s):
OSTI ID: 1595775
Grant/Contract Number:  
AC02-06CH11357; 2018-A0040801738
Resource Type:
Published Article
Journal Name:
Results in Chemistry
Additional Journal Information:
Journal Name: Results in Chemistry Journal Volume: 1 Journal Issue: C; Journal ID: ISSN 2211-7156
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Quantum Monte Carlo; Fixed-node error; Excited states; PseudopotentialEffective core potential

Citation Formats

Scemama, Anthony, Caffarel, Michel, Benali, Anouar, Jacquemin, Denis, and Loos, Pierre-François. Influence of pseudopotentials on excitation energies from selected configuration interaction and diffusion Monte Carlo. Netherlands: N. p., 2019. Web. doi:10.1016/j.rechem.2019.100002.
Scemama, Anthony, Caffarel, Michel, Benali, Anouar, Jacquemin, Denis, & Loos, Pierre-François. Influence of pseudopotentials on excitation energies from selected configuration interaction and diffusion Monte Carlo. Netherlands. doi:10.1016/j.rechem.2019.100002.
Scemama, Anthony, Caffarel, Michel, Benali, Anouar, Jacquemin, Denis, and Loos, Pierre-François. Tue . "Influence of pseudopotentials on excitation energies from selected configuration interaction and diffusion Monte Carlo". Netherlands. doi:10.1016/j.rechem.2019.100002.
@article{osti_1529010,
title = {Influence of pseudopotentials on excitation energies from selected configuration interaction and diffusion Monte Carlo},
author = {Scemama, Anthony and Caffarel, Michel and Benali, Anouar and Jacquemin, Denis and Loos, Pierre-François},
abstractNote = {Due to their diverse nature, the faithful description of excited states within electronic structure theory methods remains one of the grand challenges of modern theoretical chemistry. Quantum Monte Carlo (QMC) methods have been applied very successfully to ground state properties but still remain generally less effective than other non-stochastic methods for electronically excited states. Nonetheless, we have recently reported accurate excitation energies for small organic molecules at the fixed-node diffusion Monte Carlo (FN-DMC) within a Jastrow-free QMC protocol relying on a deterministic and systematic construction of nodal surfaces using the selected configuration interaction (sCI) algorithm known as CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively). Albeit highly accurate, these all-electron calculations are computationally expensive due to the presence of core electrons. One very popular approach to remove these chemically-inert electrons from the QMC simulation is to introduce pseudopotentials (also known as effective core potentials). Taking the water molecule as an example, we investigate the influence of Burkatzki-Filippi-Dolg (BFD) pseudopotentials and their associated basis sets on vertical excitation energies obtained with sCI and FN-DMC methods. Although these pseudopotentials are known to be relatively safe for ground state properties, we evidence that special care may be required if one strives for highly accurate vertical transition energies. Indeed, comparing all-electron and valence-only calculations, we show that using pseudopotentials with the associated basis sets can induce differences of the order of 0.05 eV on the excitation energies. Fortunately, a reasonable estimate of this shift can be estimated at the sCI level.},
doi = {10.1016/j.rechem.2019.100002},
journal = {Results in Chemistry},
number = C,
volume = 1,
place = {Netherlands},
year = {2019},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1016/j.rechem.2019.100002

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