running VASP MD simulations of liquid Beryllium at high temperatures (~ 3000 K) and constant (solid) volume. Our results show what appear to be un-physical results for the pair distribution function:
1) the nearest neighbour peak is shifted down from its position in the
crystal, with little change in the composition of the first shell,
and
2) there is a significant portion of the PDF that lies within the PAW
cutoff radius (PAW_GGA Be_sv 23Feb1998).
We think that these un-physical results could be caused by a Be PAW cutoff radius that is too big for these conditions. We have tried unsuccessfully to find information on how to generate PAW potentials for VASP, so we would like to ask if you could provide us with a harder POTPAW, or the information on how to generate it. If possible, we would like to test a couple of potentials of increasing hardness to assess the effects on the issues we are observing.
liquid Beryllium at high temperatures
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Re: liquid Beryllium at high temperatures
For most of atoms two POTCARs are available: hard and soft.
Both are developed to reproduce properties of solids.
The potentials are generated by G. Kresse using the internal code,
which is not released for the use by VASP users.
The aplicability of potentials to liquid metals was demonstrated
in a couple of papers, e.g. liquid Fe (PRB61-2000-132).
Here, in Fig. 3, a significant portion of the PDF lies within the PAW
cutoff radius and this is not considered unphysical.
Both are developed to reproduce properties of solids.
The potentials are generated by G. Kresse using the internal code,
which is not released for the use by VASP users.
The aplicability of potentials to liquid metals was demonstrated
in a couple of papers, e.g. liquid Fe (PRB61-2000-132).
Here, in Fig. 3, a significant portion of the PDF lies within the PAW
cutoff radius and this is not considered unphysical.