Hi all,
I would like to create and orient a face-centered tetragonal (FCT) lattice of a binary alloy gamma-TiAl within LAMMPS. For that, I’m using custom lattice command with the basis and primitive cell vectors. It is working fine if my lattice has cubic orientation and I do not use orient keyword. The cohesive energy (4.508 eV/atom) of the cell after minimization shows an excellent match with the reported value (4.508 eV/atom) in the EAM potential paper (Mishini 2003). Please see the input file given below.
But the problem occurs when I’m trying to orient the lattice in a desired crystallographic orientation. For example, if I use “orient x 1 1 1 orient y 1 -1 0 orient z 1 1 -2” command, the cohesive energy after minimization is 3.931 eV/atom which has a large difference with the reported value 4.508 eV/atom.
--------------------------------------Input file--------------------------------------------------------
units metal
dimension 3
boundary p p p
atom_style atomic
lattice custom 1.0 origin 0.0 0.0 0.0 &
a1 4.007 0.0 0.0 &
a2 0.0 4.007 0.0 &
a3 0.0 0.0 4.075 &
basis 0.0 0.0 0.0 &
basis 0.0 0.5 0.5 &
basis 0.5 0.0 0.5 &
basis 0.5 0.5 0.0 &
orient x 1 1 1 orient y 1 -1 0 orient z 1 1 -2
region simbox block 0 2 0 2 0 2 units lattice
create_box 2 simbox
create_atoms 2 box basis 1 1 basis 2 2 basis 3 2 basis 4 1
pair_style eam/alloy
pair_coeff * * Zope-Ti-Al-2003.eam.alloy Ti Al
neighbor 2.0 bin
neigh_modify delay 10 check yes
compute eng all pe/atom
compute eatoms all reduce sum c_eng
reset_timestep 0
fix 1 all box/relax aniso 0.0 vmax 0.001
thermo 10
thermo_style custom step pe lx ly lz xy yz xz press pxx pyy pzz c_eatoms
min_style cg
minimize 1e-16 1e-16 500000 1000000
variable natoms equal “count(all)”
variable teng equal “c_eatoms”
variable ecoh equal “v_teng/v_natoms”
print “Total energy (eV) = {teng};"
print "Number of atoms = {natoms};”
print “Cohesive energy (eV) = ${ecoh};”
write_data data_TiAl