Dear users, I'm trying to understand the format of the file containing the real space force constants output from the q2r.x program. Here is a selection of the output file for calculation of Si using a (444) grid:
4 4 4 1 1 1 1 1 1 1 2.71632979375E-01 2 1 1 -3.79717062500E-03 3 1 1 3.75093750000E-05 4 1 1 -3.79717062500E-03 1 2 1 9.08752437500E-03 2 2 1 -3.62702500000E-04 3 2 1 3.30887500000E-05 4 2 1 -3.79717062500E-03 1 3 1 4.08761312500E-03 2 3 1 -3.62702500000E-04 3 3 1 3.75093750000E-05 4 3 1 -3.62702500000E-04 ... I believe I understand the lines like "1 1 1 1" occurring above, but what are the three numbers before the value of each force constant (how do these numbers correspond to the atomic displacements?) Also, what are the units given for the force constant? Thanks in advance, Eric Landry, Ph.D. candidate Department of Mechanical Engineering, Carnegie Mellon University
