Re: Open Shell Systems
Posted: Fri Mar 21, 2014 8:44 am
Dear Vito,
See for instances:
Phys. Rev. Lett. 75, 818 (1995)
Phys. Rev. B 73, 205119 (2006).
Phys. Rev. B 73, 233103 (2006).
Best Daniele
Because you want to simulate an isolated molecule in a supercell approximation. As yambo works in plane waves, you have periodic boundary conditions and you want to avoid spurious interaction between your cell and images. So in principle vacuum has to be added until convergence is reached. Such volume effect in GW are more problematic than in DFT. In practice coulomb cutoff technique can be used, but in order to work large supercell are neeeded.Why is in the tutorial the acell for H2 molecule in the cube so large ( acell = 25 Bohr) ?
See for instances:
Phys. Rev. Lett. 75, 818 (1995)
Phys. Rev. B 73, 205119 (2006).
Phys. Rev. B 73, 233103 (2006).
No if you want to simulate a molecule and not a molecular crystal.Should it not be much lower in order to reach the minimum of the total energy as a function of acell
When you want to use coulomb cutoff technique there is a relation between the size of your system, cutoff range and supercell size.or is the value just a random number without any further meaning?
Best Daniele