Bias cancellation in one-determinant fixed-node diffusion Monte Carlo: Insights from fermionic occupation numbers

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61988987%3A17310%2F17%3AA1801N2V" target="_blank" >RIV/61988987:17310/17:A1801N2V - isvavai.cz</a>
Result on the web
<a href="https://journals.aps.org/pre/abstract/10.1103/PhysRevE.95.033308" target="_blank" >https://journals.aps.org/pre/abstract/10.1103/PhysRevE.95.033308</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/PhysRevE.95.033308" target="_blank" >10.1103/PhysRevE.95.033308</a>

Result language
angličtina
Original language name
Bias cancellation in one-determinant fixed-node diffusion Monte Carlo: Insights from fermionic occupation numbers
Original language description
The accuracy of the fixed-node diffusion Monte Carlo (FNDMC) depends on the node location of the supplied trial state ΨT. The practical FNDMC approaches available for large systems rely on compact yet effective ΨT, most often containing an explicitly correlated single Slater determinant (SD). However, SD nodes may be better suited to one system than to another, which may possibly lead to inaccurate FNDMC energy differences. It remains a challenge how to estimate nonequivalence or appropriateness of SDs. Here we use the differences of a measure based on the Euclidean distance between the natural orbital occupation number (NOON) vector of the SD and the exact solution in the NOON vector space, which can be viewed as a measure of SD nonequivalence and as a qualitative measure of the expected degree of nondynamic-correlation-related bias in FNDMC energy differences. This is explored on a set of small noncovalent complexes and covalent bond breaking of Si2 vs N2. It turns out that NOON-based measures well reflect the magnitude and sign of the bias present in the data available, thus providing insights into the nature of bias cancellation in SD FNDMC energy differences.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10301 - Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)

Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2017
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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