Extrapolation of Charge Density: Ver. 1.0
Taisuke Ozaki, RCIS, JAIST
Let us consider an extrapolation
the coordinate at the th molecular dynamic or geometry
optimization step [1,2] by a linear combination
of the previous coordinates
where for three is an optimum choice in many cases.
To fit well the coordinate
to the real
coordinate , we consider the minimization of
a function :
with respect to and .
By solving the linear equation, we may have an optimum choice of
a set of . Then, it is assumed that the difference charge
can be extrapolated well by the
same set of coefficients as
is given by the superposition of atomic
charge densities at .
Using Eq. (4) it can be possible to estimate a good input charge density
at the th step in molecular dynamic simulations or
T. A. Arias, M. C. Payne, and J. D. Joannopoulos,
Phys. Rev. B 45, 1538 (1992).
D. Alfe, Comp. Phys. Commun. 118, 32 (1999).