Dear Davide,

> 2) as you can imagine no it is not a molecule. If the problem is due to the 
> cell parameters being not orthorhombic I might consider to run on a cluster.

If the system is not a molecule, or more generally is not a *finite system* 
which can be placed in the center of the simulation cell such that it does not 
touch cell's boundaries (such that the charge density of the system is 
vanishing at the cell's boundaries), then the treatment of a dipole in real 
space (by setting d0psi_rs=.true.) is not allowed. Please see a discussion in 
Sec. 2.5 in X. Ge et al., Comput. Phys. Commun. 185, 2080 (2014). I think that 
in your case you should set d0psi_rs=.false., which would treat the dipole in 
reciprocal space by dealing with the commutator [H,r], which however currently 
does not contain a contribution from the exact-exchange potential [V_EXX,r] 
(which means that the relative (and absolute) intensities of the peaks in the 
absorption spectrum would not be correct due to the missing contribution from 
EXX in the evaluation of the matrix element of the dipole). You may also 
consider suggestions from Giuseppe in the previous post to this threa
 d, which could be a workaround to this problem, if the use of the continuum 
dielectric effective medium is a satisfactory level of approximation for your 
studies. Moreover, since we are both at EPFL we can arrange a meeting and 
discuss in person about all these issues.

> On the other hand I am genuinely too busy for coding so just in case do you 
> think comment that error and try to run the calculation could it be worthy?

I think this not a good idea because: 1) it seems to me that the routine 
"shift_d0psi" cannot be used in the case of cells with non-orthogonal lattice 
vectors (this routine has to be investigated more carefully), 2) you should not 
treat the dipole in real space if you do not have a finite system as it is 
discussed above.

HTH

Best regards,
Iurii


Dr. Iurii Timrov
Postdoctoral Researcher
Swiss Federal Institute of Technology Lausanne (EPFL)
Laboratory of Theory and Simulation of Materials (THEOS)
CH-1015 Lausanne, Switzerland





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