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Failure of density-matrix minimization methods for linear-scaling density-functional theory using the Kohn penalty-functional

P. D. Haynes and M. C. Payne

Theory of Condensed Matter, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom


We examine the recently-proposed scheme [W. Kohn, Phys. Rev. Lett. 76, 3168 (1996)] for performing linear-scaling calculations within density-functional theory by direct minimization with respect to the single-particle density-matrix using a penalty-functional to exactly enforce the idempotency constraint. We show that such methods are incompatible with standard minimization algorithms (using conjugate gradients as an example) and demonstrate that this is a direct result of the non-analytic form of penalty-functional which must be chosen to obtain a variational

principle for the total energy.

PACS numbers: 71.15.Mb

Peter Haynes