<html>Dear QE users,<br />I would like to change the masses of an already calculated dynamical matrix to evaluate the change in the frequencies induced by the isotopes (without doing DFPT again).<br />I see that dynmat and matdyn requier masses but I am wondering if the starting coefficients that are saved in the .dyn file are already multiplied by 1/sqrt(M_iM_j),<br />or if only the diagonalized matrix (frequencies and eigenvectors) takes these coefficients into account.<br />Which procedure should I do?<br /><br />Regards,<br />-------------------------------------------------------------------------------------------<br />Antoine Jay LAAS-CNRS<br /><a data-jsarwt="1" data-usg="AOvVaw2dma9pkaRKEmU1HxOZr2tk" data-ved="2ahUKEwjf2pi-4aL0AhUBxoUKHSP4AQ4QFnoECBMQAQ" href="https://www.laas.fr/public/fr/m3">ajay@laas.fr</a> 7, Avenue du Colonel Roche <br />(+33)5 61 33 79 56 BP 54200, 31031 Toulouse cedex 4 <br />Equipe<strong> M^3 M</strong>odélisation <strong>M</strong>ulti-niveaux des <strong>M</strong>atériaux <br />------------------------------------------------------------------------------------------</html>