Analytical energy gradient of Gaussian and Fourier transform (GFT) method for periodic condensed systems

 RHtriangle First-principles method with the periodic boundary conditions base on the Gaussian basis set.  RHtriangle Analytical energy-gradient formalism for the Gaussian and Fourier transform (GFT) method.  RHtriangle Fourier-transform-based DFT integration.  RHtriangle First-principles molecular dynamics (MD) simulation of water.