Trade off between the level of accuracy and required computational resources for hybrid functional NAO DFT calculations
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School of Science |
S harjoitus- ja seminaarityöt
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Date
2018
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Language
en
Pages
30 pages
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PHYS-E0441 - Physics Special Assignment V
Abstract
Density functional theory (DFT) is a widely used theory for studying the electronic structureof matter [2]. Focus of this special assignment is on DFT-calculations performed via useof numerically tabulated atom-centered orbitals (NAOs) as implemented the Fritz HaberInstitute “ab initio molecular simulations” (FHI-aims) computer program package. The focus of this work is finding a balance between accuracy and use of the computationalrecourses. This problem arises especially for bigger periodic system calculations performedvia use of the hybrid exchange–correlation functionals. This is done via producing newsettings for the calculations called intermediate-settings. Simulations performed via useof the intermediate-settings should sit nicely between the pre-existing light- and the tight-settings in both level of convergence of the calculation and the computational resourcesused. Three different methods were used while producing the new a intermediate settings for Na,K, Pt, Mo, Mn and Cr. First being decrease of the pool of basis functions, second beingadjustment to confining-potential and third being use of auxiliary basis functions. The per-formance of the new intermediate-settings is verified in five different chemical environmentsand the accuracy should translate to other chemical environments as well.Description
Keywords
density functional theory, numeric atom centered orbitals, set of basis functions, auxiliary basis function, hybrid xc-functional