Dear Layla,thanks for your reply.We run this program on a cluster with 8 nodes of two Quad-Core machines. The processor is Intel(R) Xeon(R) E5335.And the OS of the server is CentOS. Many thanks -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20110610/06138bbd/attachment.html>