On Fri, 2011-10-07 at 12:15 +0300, HASAN SAHIN wrote: > all the modes (including acoustics) are both Raman and > Infrared active. Being both R+IR active of all modes > seems unphysical. if there is no symmetry, all modes are both Raman- and IR-active P. -- Paolo Giannozzi, IOM-Democritos and University of Udine, Italy