Understanding eam/alloy potentials

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1

Hello,

I need your help trying to understand the format of the eam/alloy potentials. I have read the manual in LAMMPS and it is quite clear respect the heading lines of the potential, but after that it says that it comes the N-element sections which I don’t understand. It says:

  • line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
  • embedding function F(rho) (Nrho values)
  • density function rho® (Nr values)

Ok about line 1 of this section, but when I look the potential for Ta provided by Zhou et al. I see 5 columns of data (file attached, gotten from the link you provide for potentials). Which one is supposed to be the embedded function? Which one is the density function rho? How are these five columns interpreted?

A second question: rho® is calculated for different values of the radius. I suppose that the radius starts at zero armstrongs and increases according the dr parameter, am I right? For F(rho) and the drho parameter is the same?

Thank you very much for your help, I hope my question don’t waste much of your time.

Roger.

Ta.set (142 KB)

2

According to the LAMPS doc page, a single-element alloy file (set format, which
is allowed to only have 1 element), should have 3 arrays: F(rho),
rho(r), and phi(r).
It you look at a file in LAMMPS like
potentials/Al_zhou*alloy, that's what it has. I believe that is the
correct original
DYNAMO format.

So I don't know why the Ta one has 5 arrays. Possibly it was taken from a true
alloy file with more arrays, in which case LAMMPS will only read the 1st 3
(but they better be the correct ones).

A second question: rho(r) is calculated for different values of the radius.
I suppose that the radius starts at zero armstrongs and increases according
the dr parameter, am I right? For F(rho) and the drho parameter is the same?

this is correct.

Steve