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Accelerating the convergence of the total energy evaluation in density functional theory calculations

TitleAccelerating the convergence of the total energy evaluation in density functional theory calculations
Publication TypeJournal Article
Year of Publication2008
AuthorsZhou, BJ, Wang*, YA
JournalJ. Chem. Phys.
Volume128
Pagination084101
Date PublishedFeb
ISBN Number0021-9606
Abstract

A special feature of the Strutinsky shell correction method (SCM) [D. Ullmo et al., Phys. Rev. B 63, 125339 (2001)] and the recently proposed orbital-corrected orbital-free density functional theory (OO-DFT) [B. Zhou and Y.A. Wang, J. Chem. Phys. 124, 081107 (2006)] is that the second-order corrections are incorporated in the total energy evaluation. In the SCM, the series expansion of the total electronic energy is essentially the Harris functional with its second-order correction. Unfortunately, a serious technical problem for the SCM is the lack of the exact Kohn-Sham (KS) density rho(KS)(r) required for the evaluation of the second-order correction. To overcome this obstacle, we design a scheme that utilizes the optimal density from a high-quality density mixing scheme to approximate rho(KS)(r). Recently, we proposed two total energy density functionals, i.e., the Zhou-Wang-lambda (ZW lambda) and the Wang-Zhou-alpha (WZ alpha) functionals, for use in the OO-DFT method. If, the two interpolation parameters, X and a, are chosen to allow the second-order errors of the ZW lambda and the WZa functionals to vanish, these two functionals reduce to the Hohenberg-Kohn-Sham functional with its second-order correction. Again, the optimal density from a high-quality density mixing scheme is used to approximate rho(KS)(r) in the evaluation of X and a. This approach is tested in iterative KS-DFT calculations on systems with different chemical environments and can also be generalized for use in other iterative first-principles quantum chemistry methods. (c) 2008 American Institute of Physics.

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