Hi All, i ran dftb frequency calculation with an optimized geometry obtained with dftb . I got like10 imaginary frequencies, even big numbers over 300. Any ideas why it was so ? Thanks Sefa Nur -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20120625/58f1f918/attachment.htm>