On Sun, 2014-01-12 at 13:55 +0330, shiva mokhavat wrote: > I want to calculate phonon properties of cinnabar hexagonal structure > of HgTe, but when I run ph.x some of the frequencies are negative. why > this happen?
See http://www.quantum-espresso.org/faq/phonons/ , in particular items 7.3 and 7.2 P. -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
