Coulomb cutoff of hexagonal cell.
Posted: Thu Aug 31, 2023 5:00 pm
Dear developers,
I want to study a 0D system (a molecule of significant size, around 15 A with only a gamma point) of the point group D6h. So, I chose ibrav=4 and placed the molecule's center at (0,0,0) to detect all system symmetries instead of putting it in the center of the cell. Please, I have questions about a truncated Coulomb potential.
As I found there (viewtopic.php?t=45), the truncated Coulomb potential depends only on |r-r'| so the box or sphere or whatever is not centered at any point of the cell. If I understand, for the 0D system with a gamma point, I do not need to calculate any Random Integration, which means there is no need to mention the rim_cut option in GW and BSE inputs, do I?
If not, I'm misunderstood, so I must perform the Random Integrations. In my case, my primitive cell is hexagonal. Does it cause any problems If I choose a box or a sphere?
I want to study a 0D system (a molecule of significant size, around 15 A with only a gamma point) of the point group D6h. So, I chose ibrav=4 and placed the molecule's center at (0,0,0) to detect all system symmetries instead of putting it in the center of the cell. Please, I have questions about a truncated Coulomb potential.
As I found there (viewtopic.php?t=45), the truncated Coulomb potential depends only on |r-r'| so the box or sphere or whatever is not centered at any point of the cell. If I understand, for the 0D system with a gamma point, I do not need to calculate any Random Integration, which means there is no need to mention the rim_cut option in GW and BSE inputs, do I?
If not, I'm misunderstood, so I must perform the Random Integrations. In my case, my primitive cell is hexagonal. Does it cause any problems If I choose a box or a sphere?