On Tue, 2013-06-18 at 12:38 +0430, Mohsen Modaresi wrote: > 1) The Dynamical Matrix is calculated for two q points in each > ***.dyn** files.
this means that there are two q points in the star (the set of q-points that are equivalent by symmetry) > But the Diagolnalization is done for only the first q point. the diagonalization for the second point would give the same results, since the two points are equivalent by symmetry > I can not understand what is the necessity of the second q point? I don't think there is any necessity, but you have all q points (and not just the irreducible segment) for free. > 2) I expect a (3Nat*3Nat) for dynamical matrix so the eigen vectro > which are written in the end of file should be a (1*3*Nat) matrix but > instead i see a (3*3) matrix, for example (Real+Imaginary), > omega( 1) = 7.786434 [THz] = 259.729218 [cm-1] > > ( 1.000000 0.000000 0.000087 0.000000 -0.000130 0.000000 ) > ( 0.000344 0.000000 0.000028 0.000000 -0.000144 0.000000 ) > ( -0.000346 0.000000 0.000095 0.000000 -0.000016 0.000000 ) is this what you see between lines " omega( 1) =" and " omega( 1) ="? then you have the real and imaginary parts of x, y, z displacements, or maybe eigenvectors, for the three atoms in the unit cell > 3) I also worked with Vibra in the Siesta package. In this code the > positive and negative displacement for atoms in each direction is > considered but i can not find the same procedure in the ph.x. see above. For a generic q point, eigenvectors of the dynamical matrix are complex. P. -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222