ABINIT Discussion Forums

hello everybody
I ran rf1 lesson for LaCoO3 in rhombohedral phase and these are my results
I don't know which are Lo and which are TO?
thanks

46.067 84.397 143.045
152.072 151.161 125.892
201.417 178.200 174.951
303.609 299.699 264.055
323.236 318.019 304.935
412.377 355.282 338.717
492.908 488.499 465.782
504.191 494.961 494.727
551.117 550.738 517.071
589.147 566.245 564.238

Please check Ashcroft and Mermin or something for the definitions.

The frequencies are not useful. You should compute the scalar product between the displacement vectors (in the anaddb output) and the q-point. For Gamma it's more delicate, obviously, and you need to (with the rf tutorials) calculate the non-analytical correction to the dynamical matrix, for q -> limits in different directions (x, y, z) which now give the vector you should be doing the scalar product with. The correction should displace the LO mode up and leave the TO mode more or less where it was (so compare the frequencies with and without E field).

matthieu