Increase precision of phDOS output (frequency and total DOS) in matdyn.x
The phonon density of states (phDOS) generated by PH/matdyn.x is used in a number of post-processing tools to calculate thermodynamic properties such as the vibrational entropy or Helmholtz free energy. This is done by quadrature over the phDOS times a function of the frequency. For these integrals to converge to a reasonable degree wrt the frequency quadrature, one needs a step of deltaE = 0.01 cm-1 or lower, which is smaller than the current precision in the output of matdyn.x (hence, one would end up with 10s of frequencies that are all the same in the first column). This MR increases the precision in the output for the first two columns of the phdos file by six decimal places.