Elk

Thanks for responding, Kay! Actually I’m asking because I can’t obtain a correct dispersion curves for metals. Even while trying to perform the Al-phonon example I obtain something like
next picture: http://anticultura.narod.ru/2.jpg . As you can see two branches are degenerated i.e. coincide. Unfortunately, I get the same result for other metals. I have not tried to perform the Si-phonon example, where a nice and correct picture is attached. But also a question is – why on this Si picture there are so many branches – does Elk support optical modes calculation?