Density-functional molecular dynamics with real-space finite difference.

A real-space scheme based on density-functional molecular dynamics is presented. Two issues are addressed. One is the use of an {ital exact} finite-difference form of the kinetic-energy operator within a supercell geometry. The second is the introduction of a preconditioning operation in real space. Numerical tests with ultrasoft pseudopotentials show satisfactory accuracy and efficiency of the present real-space scheme.