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lammps/examples/USER/mgpt/in.vac0-bcc
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# script for mgpt t=0 eos with unrelaxed vacancy in bcc lattice:
# input for unrelaxed vacancy formation energy at constant atomic volume
echo screen
units electron
atom_style atomic
# Atomic volume for MGPT potential in a.u.
variable atomic_vol equal 121.6
# Derive effective lattice volume from atomic volume for 249-site cell
variable lat_vol equal ${atomic_vol}*249/250
# Derive lattice constant from lattice volume
variable lattice_constant equal (${lat_vol}*2.0)^(1.0/3.0)
# Create bcc lattice with 5x5x5 unit cells (250 atoms)
lattice bcc ${lattice_constant}
region box block 0 5 0 5 0 5
create_box 1 box
create_atoms 1 box
# Remove central atom from bcc lattice to create vacancy
region vacancy sphere 2.5 2.5 2.5 0.1 units lattice
delete_atoms region vacancy
# Define potential for use in simulation
pair_style mgpt
# Set parameters for potential:
# parameter files atomic volume
#pair_coeff * * parmin potin ${atomic_vol}
pair_coeff * * Ta6.8x.mgpt.parmin Ta6.8x.mgpt.potin ${atomic_vol}
# Create velocities at 0 K
velocity all create 0.0 87287
# Set neighbor list parameters
neighbor 0.1 bin
neigh_modify every 1 delay 0 check yes
# Set up microcanonical integrator
fix 1 all nve
# Dump coordinates to file every 50 timesteps
dump id all atom 50 dump.vac0-bcc
# Output thermodynamical data every 10 timesteps
thermo 10
# Set output quantities and output format
thermo_style custom step vol temp pe etotal press
## Example: Output floating point number with 5 digits exponential notation.
#thermo_modify format float %15.5e
# Run 0 timesteps
run 0
# Convert energy to rydbergs and pressure to gpa
variable natoms equal "count(all)"
variable voltot equal "vol"
variable atvol equal "v_voltot/v_natoms"
variable etot equal "2.0*pe"
variable etotry equal "v_etot/v_natoms"
variable ptot equal "press"
variable ptotgpa equal "v_ptot/1.0e+09"
print "number of atoms = ${natoms}"
print "atomic volume (a.u.) = ${atvol}"
print "total energy (ry/atom) = ${etotry}"
print "pressure (gpa) = ${ptotgpa}"
print "${natoms} ${atvol} ${etot} ${ptotgpa}"
print "${atvol} ${etotry} ${ptotgpa}"
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