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dc.contributor.authorOvery, Catherine
dc.contributor.authorBooth, George H
dc.contributor.authorBlunt, NS
dc.contributor.authorShepherd, James J
dc.contributor.authorCleland, Deidre
dc.contributor.authorAlavi, Ali
dc.date.accessioned2018-11-14T00:32:06Z
dc.date.available2018-11-14T00:32:06Z
dc.date.issued2014-12-28
dc.identifier.issn0021-9606
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/285074
dc.description.abstractProperties that are necessarily formulated within pure (symmetric) expectation values are difficult to calculate for projector quantum Monte Carlo approaches, but are critical in order to compute many of the important observable properties of electronic systems. Here, we investigate an approach for the sampling of unbiased reduced density matrices within the full configuration interaction quantum Monte Carlo dynamic, which requires only small computational overheads. This is achieved via an independent replica population of walkers in the dynamic, sampled alongside the original population. The resulting reduced density matrices are free from systematic error (beyond those present via constraints on the dynamic itself) and can be used to compute a variety of expectation values and properties, with rapid convergence to an exact limit. A quasi-variational energy estimate derived from these density matrices is proposed as an accurate alternative to the projected estimator for multiconfigurational wavefunctions, while its variational property could potentially lend itself to accurate extrapolation approaches in larger systems.
dc.format.mediumPrint
dc.languageeng
dc.publisherAIP Publishing
dc.titleUnbiased reduced density matrices and electronic properties from full configuration interaction quantum Monte Carlo.
dc.typeArticle
prism.issueIdentifier24
prism.publicationDate2014
prism.publicationNameJ Chem Phys
prism.startingPage244117
prism.volume141
dc.identifier.doi10.17863/CAM.32444
rioxxterms.versionofrecord10.1063/1.4904313
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.licenseref.startdate2014-12
dc.contributor.orcidBlunt, Nicholas [0000-0002-2284-6969]
dc.contributor.orcidAlavi, Ali [0000-0002-0654-9489]
dc.identifier.eissn1089-7690
rioxxterms.typeJournal Article/Review
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/J003867/1)
rioxxterms.freetoread.startdate2015-12-31


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