Conversion for eam potential to use with units real

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1

Hi,

I have a gold-water system in which the gold atoms are paired using an eam potential given by the file ‘Au-u3.eam’. In the LAMMPS manual, section eam potentials (http://lammps.sandia.gov/doc/pair_eam.html) advises us to use the pair_coeff with metal units and also the following:

2

Why can’t you just use metal units and convert the results after the simulation?

Axel

3

Yes, it is much easier to convert your water model to metal units than to convert EAM to real units. This just requires applying a factor of 1ev/1kcal/mol=23.06 to every energy and force parameter in the water model:

…/update.cpp:158: force->qe2f = 23.060549;

Also, don’t forget to change your timestep size to ps.

Either way, there is no point asking the LAMMPS list if you have done it correctly. We cannot check ever detail of your work. Instead, you should construct a suitable test that will clearly expose likely errors.

Regardless of which unit style you use, there is no need to change the units of rho, since it is only an intermediate quantity and is not used by other parts of LAMMPS outside of the EAM pair_style.

Aidan