<html><body><div style="color:#000; background-color:#fff; font-family:新宋体, nsimsun, sans-serif;font-size:13pt">Hi Jun, Please have a look at this paper (the smooth method part): J. VandeVondele et al. / Computer Physics Communications 167 (2005) 103–128 Title: QUICKSTEP Fast and accurate density functional calculations using a mixed Gaussian and plane waves approach Regards, SUN CUHK </div></body></html>