interatomic potentials

[brsahu]

Dear Vaspusers,

Using LVTOT tag one can get (in the file LOCPOT) the total electrostatic potential in a unit cell or electrostatic+exchg.corrleation potential in the unit cell.

The description of LVTOT tag in the manual says LOCTOT file
also contains average electrostatic potential 'at each ion' and can
calculate, I guess, avg. electrostatic+exchg.correlation potential
'at each ion'.

I have a supercell system with only one impurity atom.
I am interested in knowing the interatomic potential between
this impurity atom and a host atom. Say one Mn impurity in Ge
so I am looking for interatomic potential between this impurity
atom and a Ge atom in the host.

Can the avg potential (from LOCPOT file) at the impurity atom
be taken as the interatomic potential (between the impurity atom and a host atom)?

Can anyone explain how this avg potential at the ion site is calculated in vasp? Manual says (the first equation in LVTOT tag description) it is calculated by putting one test charge with norm 1. But I can not figure out why we have to put a test charge on
the ion site to calculate the avg. potential.

sahu

[brsahu]

Dear Vasp users,

Do any users have suggestions to the above query?

sahu

[konglt]

I guess you misunderstand the meaning of electrostatic potential, which means the potential felt by an electron in the field of ions (or atoms). It has nothing to do with the interatomic potential.

The obtained LOCPOT file can be used to get the work function of a specific surface by using a supercell.

LT