<div dir="ltr"><div>One thing that confuse me is the irreducible BZ k-points in phonon calculation. <br> We use a q-points mesh in order to get the interatomic force constant. <br> becuase of crystal symmetry we need not to calcaculate all the q points but a minimum of irreducible q-points. </div>
<div> And in non-selfconsistent calculation of electron structure with fixed charge for a give q point . why we should use the symmetry of samll group of S(q) ? The group of S(q) is a subgroup of crystall lattice symmetry group S(L) ,what it the difference between these two symmetry group, how to determine S(q) from S(L)? so is this subgroup of S(q) determines the phonon mode at point q ? <br>
<br><br clear="all"><br>-- <br>Sincerely Y. M. Qian <br>Lab.of Condensed Matter Theory and Materials Computation <br>Institute of Physics <br>Chinese Academy of Sciences<br>Tel: + 8610 8264 9147<br><a href="mailto:E-Mail%3Ayuminqian@gmail.com" target="_blank">E-Mail:yuminqian@gmail.com</a> <br>
P.O.Box 603 Beijing 100190<br>China <br><br></div></div>