updates "add eco df"

   * :doc:`oneway <fix_oneway>`

   * :doc:`orient/bcc <fix_orient>`

   * :doc:`orient/fcc <fix_orient>`

   * :doc:`orient/eco <fix_orient_eco>`

   * :doc:`phonon <fix_phonon>`

   * :doc:`pimd <fix_pimd>`

   * :doc:`planeforce <fix_planeforce>`

..  index:: fix eco/force

..  index:: fix orient/eco

fix eco/force command

=====================

fix orient/eco command

======================

.. parsed-literal::

   fix ID group-ID eco/force u0 eta rcut file

   fix ID group-ID orient/eco u0 eta rcut orientationsFile

* ID, group-ID are documented in fix command

* u0 = energy added to each atom (energy units)

* eta = cutoff value (usually 0.25)

* rcut = cutoff radius for orientation parameter calculation 

* file = file that specifies orientation of each grain

* orientationsFile = file that specifies orientation of each grain

Examples

""""""""

.. code-block:: LAMMPS

   fix gb all eco/force 0.08 0.25 3.524 sigma5.ori 

   fix gb all orient/eco 0.08 0.25 3.524 sigma5.ori 

Description

experience a synthetic force as its surrounding is that of an oriented single crystal 

and thermal fluctuations are masked by the parameter eta. Near the grain boundary 

however, the gradient is nonzero and synthetic force terms are computed. 

The orientation file specifies the perfect oriented crystal basis vectors for the 

two adjoining crystals. The first three lines for the energetically penalized and the 

The orientationsFile specifies the perfect oriented crystal basis vectors for the 

two adjoining crystals. The first three lines (line=row vector) for the energetically penalized and the 

last three lines for the energetically favored grain assuming u0 is positive. For 

negative u0 this is reversed. With the rcut parameter, the size of the region around 

each atom which is used in the order parameter computation is defined. It should at 

negative u0, this is reversed. With the rcut parameter, the size of the region around 

each atom which is used in the order parameter computation is defined. rcut must be 

smaller than the interaction range of the MD potential. It should at 

least include the nearest neighbor shell. For high temperatures or low angle 

grain boundaries, it might be beneficial to increase rcut in order to get a more 

precise identification of the atoms surrounding. However, computation time will 

increase as more atoms considered in the order parameter and force computation. 

increase as more atoms are considered in the order parameter and force computation. 

It is also worth noting that the cutoff radius must not exceed the communication 

distance for ghost atoms in LAMMPS. Currently however, the method stores results 

for order parameter and force computations in statically allocated arrays to 

increase efficiency such that the user is limited to 24 nearest neighbors. 

This is more than enough in most applications. With file, the input file for 

the 6 oriented crystal basis vectors is specified. Each line of the input file 

This is more than enough in most applications. With orientationsFile, the  

6 oriented crystal basis vectors is specified. Each line of the input file 

contains the three components of a primitive lattice vector oriented according to 

the grain orientation in the simulation box. The first (last) three lines correspond 

to the primitive lattice vectors of the first (second) grain. An example for 

a :math:`\Sigma\langle001\rangle` misorientation is given at the end.

If no synthetic energy difference between the grains is created, u0=0, the 

force computation is omitted. In this case, the order parameter of the 

driving force can be used to track the grain boundary motion throughout the 

force computation is omitted. In this case, still, the order parameter of the 

driving force is computed and can be used to track the grain boundary motion throughout the 

simulation.

**Restart, fix_modify, output, run start/stop, minimize info:**

No information about this fix is written to :doc: `binary restart files`.

No information about this fix is written to :doc: `binary restart files <restart>`.

The :doc:`fix_modify <fix_modify>` *energy* option is supported by this fix to 

add the potential energy of atom interactions with the grain boundary 

The total sum of added synthetic potential energy is computed and can be accessed 

by various output options. The order parameter as well as the thermally masked 

output parameter are stored in per-atom arrays and can also be accessed by various 

output commands. 

:doc:`output commands <Howto_output>`. 

No parameter of this fix can be used with the start/stop keywords of the run command. This fix is

not invoked during energy minimization.

Restrictions

""""""""""""

This fix is part of the MISC package. It is only enabled if LAMMPS was

This fix is part of the USER-MISC package. It is only enabled if LAMMPS was

built with that package. See the :doc:`Build package <Build_package>` doc page for more info.

:doc:`fix_modify <fix_modify>`

:doc:`fix_orient <fix_orient>` 

**Default:** none

----------

log eam.log

log log.orient_eco

dimension 3

boundary p p p

units metal

atom_style atomic

lattice fcc 3.5

read_data examples/eco_force/sigma5.lammps

pair_style eam/fs

pair_coeff * * examples/eco_force/Ni.eam.fs Ni

read_data examples/USER/misc/orient_eco/sigma5.lammps

pair_style eam

pair_coeff * * potentials/Ni_u3.eam

timestep 0.001

thermo 100

fix integrator all npt temp 750 750 0.1 iso 0 0 0.1

fix eco all eco/force 0.08 0.25 3.6 examples/eco_force/sigma5.ori

fix eco all orient/eco 0.08 0.25 3.6 examples/USER/misc/orient_eco/sigma5.ori

thermo 100

thermo_style custom step temp etotal press vol f_eco

velocity all create 750 1

dump save all custom 100 nidata_eam.dump xs ys zs f_eco[1] f_eco[2]

dump save all custom 100 orient_eco.dump xs ys zs f_eco[1] f_eco[2]

dump_modify save sort id

run 1000