## IMD |
## MEAM Potentials (option meam)The Modified Embedded Atom Method was formulated by Baskes
(M.I.Baskes, The total energy for the MEAM potentials have a form similar to the EAM potentials: Here rho is the electron density at the position of atom
_{i}i, phi is a pair potential, and
_{ij}S is the screening function defined below._{ij}For MEAM potentials, the electron density is given by where the parameters rho,
^{(s)}_{i}s=0,...,3, are partial electron densities defined byThe functions L(^{(0)}z) = 1, L(^{(1)}z)
= z, L(^{(2)}z) =
z^{2}-1/3, L(^{(3)}z) =
z^{3}-3/5z. The atomic electron density
functions from atom j at a distance r from
atom _{ij}i areHere, r, and
^{0}_{i}beta are parameters,
^{(s)}_{i}f is a cutoff function, and _{c}S
is the screening function._{ij}The many-body screening function i and j is defined as the product of the screening
factors S due to all other neighbour atoms _{ikj}k
of i and j,
where C are parameters and the function
^{0}_{kij}g is defined as_{c}The cutoff function where Delta_r is the width of the cutoff region._{ij}The indices of the parameters refer to the atom types involved. The following IMD parameters correspond to the MEAM potential parameters:
The pair potential core_potential_file.The embedding energy function embedding_energy_file. Alternatively, IMD computes the
embedding energy analytically according toIn this case, the parameters have to be specified using the following IMD parameters:
The atomic electron density functions
rho,
however, can be read in as a potential table using the IMD parameter
^{a(0)}_{i}(r)el_density_file.The many-body interactions of the MEAM potential are computed using
neighbour tables. In constrast to the covalent potentials the IMD
parameter If more than one atom type are used, common values of the
parameters The screening function meam_cmin
and meam_cmax to be equal. |