> Dears Siesta Users > > I am new using siesta and doing some tests I have the following question > ¿How I can obtain the vibrational frequencies with siesta? This step is > carried out in the optimization of geometry or it is a different step. I > read the manual and I found that siesta can calculate the constants of > force > and utilizing the program Vibra to examine the output file. However even I > am confused: Does Siesta calculate the vibrational frequencies or I must > obtain them from other package (Vibra for example)?
Dear Diego: Siesta produces force constants and stores them in the .FC file. This is a special calculation, done in "FC" regime (Type of Ryn) after you achieved the geometry optimization (which is done in the "CG" regime). Then, in order to get frequencies, you must ran Vibra. Best regards Andrei Postnikov
