<HTML><HEAD><META content="text/html; charset=x-user-defined" http-equiv="Content-Type"><style type="text/css"><!--.MailHeader { font-family: "Arial"; font-size: 8pt; color: #000000; font-style: normal; font-weight: normal; text-decoration: none; }//--></style></HEAD><BODY><br ><font size="2" face="Arial">Hi! I am a new user of QEspresso. I want to use it to calculate the phonon dispersion for MgH2 along the following high symmetry points: Gamma to X to M to Gamma to Z to R to A to Z.<br ><br >But I am not being able to construct the matdyn.in file. How does one decide on the number of q-points? And how to go about creating this list of q-points to be used in matdyn.in?<br ><br >I have already obtained the IFC's and the following is the resulting q2r.out file:<br ><br > reading grid info from file dyn0<br > reading force constants from file dyn1<br > Dielectric Tensor not found<br > nqs= 1<br > q= 0.00000000 0.00000000 0.00000000<br > reading force constants from file dyn2<br > nqs= 1<br > q= 0.00000000 0.00000000 -0.74850299<br > reading force constants from file dyn3<br > nqs= 2<br > q= 0.00000000 -0.50000000 0.00000000<br > q= 0.50000000 0.00000000 0.00000000<br > reading force constants from file dyn4<br > nqs= 2<br > q= 0.00000000 -0.50000000 -0.74850299<br > q= 0.50000000 0.00000000 -0.74850299<br > reading force constants from file dyn5<br > nqs= 1<br > q= -0.50000000 -0.50000000 0.00000000<br > reading force constants from file dyn6<br > nqs= 1<br > q= -0.50000000 -0.50000000 -0.74850299<br > q-space grid ok, #points = 8<br ><br > fft-check success (sum of imaginary terms < 10^-12)<br ><br >Thanks in advance.<br >Tuhina<br ></font></BODY></HTML>