Dear all, I would like to have some clarifications on the units used in dynamical matrix files produced by the ph.x program in the QE suite.
At the beginning of dynamical matrix file the masses are not expressed in the same units as in the input files used for pw.x, that is [amu]. It seems to me that in the dynamical matrix file the masses could be in atomic units, which I would say correspond to electron masses. So there should be a conversion factor 1 amu = (1.660538782 ? 10^-27 kg / 9.1093826 ? 10^-31 kg) me = 1822.8884 me However there is still a factor 1/2 to include to pass from the amu values to those reported at the beginning of the dynamical matrix file. Am I right? Why the 1/2 factor? And what are the typical units used for force constants? Thanks a lot. Cristian -- ___________________________________________________ Cristian Degli Esposti Boschi CNR, CNISM, Unita' di Ricerca di Bologna, c/o Dipartimento di Fisica, Universita' di Bologna viale Berti-Pichat, 6/2, 40127, Bologna, Italia tel. ++39 051 2095114 fax ++39 051 2095113 e-mail: cristian.degliesposti -AT- unibo.it web: http://www.df.unibo.it/fismat/theory ___________________________________________________