On reality of dynamical matrix
arXiv:1612.09148
Abstract
The symmetry properties of the dynamical matrix are well described in multiple classic textbooks. This short paper revisits the issue to demonstrate alternative form of dynamical matrix which explicitly shows its symmetry and reality in common cases.
The second equality in eq. 11 does not hold for the general case. Thus, the conclusion does not follow from the premises and the claim of the paper is not proven