[CPMD-list] External Potential keyword

[Hugh Wilson]

Hi all. I'm trying to add an external electric field to my
simulations, and I'm assuming that the undocumented EXTERNAL POTENTIAL
keyword will do what I want. From the code it seems that I have to specify
the external potential in a binary file called extpot.unfo.grid, but it's not
clear to me how I should lay this file out.

There seem to be two READ statements - the second one which reads EXTPOT
seems clear enough, but the first one which reads something called PSCR
has me puzzled. It's also not clear to me how many entries I need to
specify the potential (nr1*nr2s*nr3s, but I don't know what these mean)
nor what units are used to specify the potential.

If anyone knows how this section of the code works, I'd greatly appreciate
some advice.

Thanks,

Hugh Wilson
Nanoscale Simulation Laboratory
School of Physics
University of Sydney