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Phys. Rev. B 48, 14646–14649 (1993)

Unconstrained minimization approach for electronic computations that scales linearly with system size

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Pablo Ordejón
Department of Physics, University of Illinois, Urbana, Illinois, 61801

David A. Drabold
Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701-2979

Matthew P. Grumbach and Richard M. Martin
Department of Physics, University of Illinois, Urbana, Illinois, 61801

Received 8 March 1993; published in the issue dated 15 November 1993

We present a method for the calculation of total energies and forces that scales linearly with the number of atoms in the system. The key points are (i) an unconstrained conjugate gradient minimization of the electronic energy that avoids the need of explicit orthonormalization, and (ii) description of the electrons in terms of localized wave functions, truncated beyond a radius Rc. The method is variational, giving an upper bound to the exact total energy, and is exact as Rc→∞. We test the method for a model tight-binding Hamiltonian, and in full ab initio molecular-dynamics calculations.

© 1993 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.48.14646
DOI:
10.1103/PhysRevB.48.14646
PACS:
71.20.Ad, 02.60.Dc, 61.46.+w