128 lines
4.1 KiB
ReStructuredText
128 lines
4.1 KiB
ReStructuredText
.. index:: pair_style eam/apip
|
|
.. index:: pair_style eam/fs/apip
|
|
|
|
pair_style eam/apip command
|
|
=============================
|
|
|
|
Constant precision variant: *eam*
|
|
|
|
pair_style eam/fs/apip command
|
|
================================
|
|
|
|
Constant precision variant: *eam/fs*
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
pair_style eam/apip
|
|
pair_style eam/fs/apip
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
pair_style hybrid/overlay eam/fs/apip pace/precise/apip lambda/input/csp/apip fcc cutoff 5.0 lambda/zone/apip 12.0
|
|
pair_coeff * * eam/fs/apip Cu.eam.fs Cu
|
|
pair_coeff * * pace/precise/apip Cu_precise.yace Cu
|
|
pair_coeff * * lambda/input/csp/apip
|
|
pair_coeff * * lambda/zone/apip
|
|
|
|
|
|
Description
|
|
"""""""""""
|
|
Style *eam* computes pairwise interactions for metals and metal alloys
|
|
using embedded-atom method (EAM) potentials :ref:`(Daw) <Daw2>`. The total
|
|
energy :math:`E_i` of an atom :math:`i` is given by
|
|
|
|
.. math::
|
|
|
|
E_i^\text{EAM} = F_\alpha \left(\sum_{j \neq i}\ \rho_\beta (r_{ij})\right) +
|
|
\frac{1}{2} \sum_{j \neq i} \phi_{\alpha\beta} (r_{ij})
|
|
|
|
where :math:`F` is the embedding energy which is a function of the atomic
|
|
electron density :math:`\rho`, :math:`\phi` is a pair potential interaction,
|
|
and :math:`\alpha` and :math:`\beta` are the element types of atoms
|
|
:math:`i` and :math:`j`. The multi-body nature of the EAM potential is a
|
|
result of the embedding energy term. Both summations in the formula are over
|
|
all neighbors :math:`j` of atom :math:`i` within the cutoff distance.
|
|
EAM is documented in detail in :doc:`pair_style eam <pair_eam>`.
|
|
|
|
The potential energy :math:`E_i` of an atom :math:`i` of an adaptive-precision
|
|
interatomic potential (APIP) according to :ref:`(Immel) <Immel2025_5>` is given by
|
|
|
|
.. math::
|
|
|
|
E_i^\text{APIP} = \lambda_i E_i^\text{(fast)} + (1-\lambda_i) E_i^\text{(precise)}\,,
|
|
|
|
whereas the switching parameter :math:`\lambda_i` is computed
|
|
dynamically during a simulation by :doc:`fix lambda/apip <fix_lambda_apip>`
|
|
or set prior to a simulation via :doc:`set <set>`.
|
|
|
|
The pair style *eam/fs/apip* computes the potential energy
|
|
:math:`\lambda_i E_i^\text{EAM}` and the
|
|
corresponding force and should be combined
|
|
with a precise potential like
|
|
:doc:`pair_style pace/precise/apip <pair_pace_apip>` that computes the
|
|
potential energy :math:`(1-\lambda_i) E_i^\text{(precise)}` and the
|
|
corresponding force via :doc:`pair_style hybrid/overlay <pair_hybrid>`.
|
|
|
|
Mixing, shift, table, tail correction, restart, rRESPA info
|
|
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
|
|
|
|
For atom type pairs I,J and I != J, where types I and J correspond to
|
|
two different element types, mixing is performed by LAMMPS as
|
|
described above with the individual styles. You never need to specify
|
|
a pair_coeff command with I != J arguments for the eam/apip styles.
|
|
|
|
This pair style does not support the :doc:`pair_modify <pair_modify>`
|
|
shift, table, and tail options.
|
|
|
|
The eam/apip pair styles do not write their information to :doc:`binary
|
|
restart files <restart>`, since it is stored in tabulated potential
|
|
files. Thus, you need to re-specify the pair_style and pair_coeff
|
|
commands in an input script that reads a restart file.
|
|
|
|
The eam/apip pair styles can only be used via the *pair* keyword of the
|
|
:doc:`run_style respa <run_style>` command. They do not support the
|
|
*inner*, *middle*, *outer* keywords.
|
|
|
|
----------
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
|
|
This pair styles are part of the APIP package. It is only enabled if
|
|
LAMMPS was built with that package. See the :doc:`Build package
|
|
<Build_package>` page for more info.
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`pair_style eam <pair_eam>`,
|
|
:doc:`pair_style hybrid/overlay <pair_hybrid>`,
|
|
:doc:`fix lambda/apip <fix_lambda_apip>`,
|
|
:doc:`fix lambda_thermostat/apip <fix_lambda_thermostat_apip>`,
|
|
:doc:`pair_style lambda/zone/apip <pair_lambda_zone_apip>`,
|
|
:doc:`pair_style lambda/input/apip <pair_lambda_input_apip>`,
|
|
:doc:`pair_style pace/apip <pair_pace_apip>`,
|
|
:doc:`fix atom_weight/apip <fix_atom_weight_apip>`
|
|
|
|
Default
|
|
"""""""
|
|
|
|
none
|
|
|
|
----------
|
|
|
|
.. _Immel2025_5:
|
|
|
|
**(Immel)** Immel, Drautz and Sutmann, J Chem Phys, 162, 114119 (2025)
|
|
|
|
.. _Daw2:
|
|
|
|
**(Daw)** Daw, Baskes, Phys Rev Lett, 50, 1285 (1983).
|
|
Daw, Baskes, Phys Rev B, 29, 6443 (1984).
|