Dear SIESTA users, I am trying to calculate the optical properties of graphene-based material. Despite very clear explanations of the related options in the manual I experience some problems in running jobs with OpticalCalculation option set to be true.
Here's the problem. This is a part of my .fdf file related to description of optical calculations presets: OpticalCalculation .true. %block Optical.Mesh 5 5 1 %endblock Optical.Mesh Optical.PolarizationType unpolarized %block Optical.Vector 0.0 0.0 1.0 %endblock Optical.Vector For a two-dimensional system, lying on XY plane, I specified the vector of light propagation along Z-coordinate (if I understood correctly the meaning of block Optical.Vector) and a mesh size used for the integration over the Brillouin zone accounting that my system is a 2D system. At the end of the output file I got massage which says "MINVEC: BASIS VECTORS ARE LINEARLY DEPENDENT". No optical properties were calculated. What basis vectors does SIESTA talk about, and what is meant by their linear dependence? It strange that this error appears only if I use OpticalCalculation .true., without it no such error appears. Do you have any solution to this problem? Another question is related to the general meaning of MeshSize, could you comment it and how to effectively use this option? One more concern is about reciprocal orientation of a system in question and the vector direction for the electric field, are they supposed to correlate meaning that the set of coordinates for the electric field vector and system of study is the same? Many Thank's for help,
