Relation between lattice size and potential energy.

Hi,
I am referring to a paper on SiO2 where the authors mention the potential energy calculated after a few MD steps is -20.0937.The modified tersoff potential, SiO.tersoff potential has been used for creating the crystal with size (44.040.644.2) A^3.

Since SiO2 crystal has 2 lattice vectors of equal length and the 3rd vector of a different length, what are the individual lattice vectorlengths of the size in Angstroms mentioned above? This info was written vaguely in the paper.

I think the potential energy/SiO2 is not related to the size of the lattice vectors. But, for various lengths, I am getting a different potential energy. Is P.E. related to the size of the crystal? a fast reply would be helpful.

Regards,
Bharadwaj.

Hi,
I am referring to a paper on SiO2 where the authors mention the potential
energy calculated after a few MD steps is -20.0937.The modified tersoff
potential, SiO.tersoff potential has been used for creating the crystal with
size (44.0*40.6*44.2) A^3.

Since SiO2 crystal has 2 lattice vectors of equal length and the 3rd vector
of a different length, what are the individual lattice vectorlengths of the
size in Angstroms mentioned above? This info was written vaguely in the
paper.

I think the potential energy/SiO2 is not related to the size of the lattice
vectors

you are thinking wrong. often the lattice constant is determined
by fitting total energies at difference lattice constants to an
equation of state.

axel.

But, for various lengths, I am getting a different potential
energy. Is P.E. related to the size of the crystal?

Are you outputting the PE normalized by the number of atoms or not?
For a perfect crystal, PE/atom is a constant, independent of the size
or your system.

Steve