Nanosurf Lab

script file

alat=" 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0"
for i in $alat;
do
 echo $i
 mkdir $i
 lattice="`echo $i`";
 sed "s/AAA/$lattice/g"  fireball.sample > fireball.in;
 ./runTG.com > a-$i.out
 grep "etot/atom" a-$i.out | cut -b50-65
 mv CHARGES $i/
 mv a-$i.out $i/
done

fireball.sample

&OPTION
basisfile = C1.bas
lvsfile = C1.lvs
kptpreference = C1.32.kpts
nstepf = 1
ifixcharge = 0
iqout = 1
rescal = AAA
&END
&OUTPUT
iwrteigen = 1
&END

atomic coordinates are defined in C.bas file C¹(0.0, 0.0) and C²(√3/3, 0.0):

      2
6  0.0000000  0.00000000  0.00000000
6  0.57735027 0.00000000 0.00000000

lattice vector a1(√3/2, 0.5); a2(√3/2, -0.5):

0.8660254   0.5000000   0.00000000
0.8660254  -0.5000000   0.00000000
0.00000000  0.00000000  60.00000000

The full Brillouine Zone (BZ) was sampled by 8×8 (Monkhorst-Pack grid). But for the energy optimization just Irreducible BZ (IBZ( is needed. In this case applying inversion symmetry we will get 32 k-points from 64 k-points for sampling the IBZ. The SCF solution has been obtained using 32 k-points, in file C1.32.kpts:

          32
 -3.17414904    0.00000000    0.00000000           0.03125000
 -2.72069907   -0.78539819    0.00000000           0.03125000
 -2.26724935   -1.57079637    0.00000000           0.03125000
 -1.81379938   -2.35619450    0.00000000           0.03125000
 -1.36034954   -3.14159274    0.00000000           0.03125000
  2.72069911    2.35619441    0.00000000           0.03125000
  3.17414895    1.57079641    0.00000000           0.03125000
  3.62759880    0.78539840    0.00000000           0.03125000
 -2.72069907    0.78539819    0.00000000           0.03125000
 -2.26724935    0.00000000    0.00000000           0.03125000
 -1.81379938   -0.78539819    0.00000000           0.03125000
 -1.36034954   -1.57079637    0.00000000           0.03125000
 -0.90689969   -2.35619450    0.00000000           0.03125000
 -0.45344985   -3.14159274    0.00000000           0.03125000
  0.00000000   -3.92699099    0.00000000           0.03125000
 -3.17414895    1.57079641    0.00000000           0.03125000
 -2.26724935    1.57079637    0.00000000           0.03125000
 -1.81379938    0.78539819    0.00000000           0.03125000
 -1.36034954    0.00000000    0.00000000           0.03125000
 -0.90689969   -0.78539819    0.00000000           0.03125000
 -0.45344985   -1.57079637    0.00000000           0.03125000
  0.00000000   -2.35619450    0.00000000           0.03125000
  0.45344985   -3.14159274    0.00000000           0.03125000
 -2.72069911    2.35619441    0.00000000           0.03125000
 -1.81379938    2.35619450    0.00000000           0.03125000
 -1.36034954    1.57079637    0.00000000           0.03125000
 -0.90689969    0.78539819    0.00000000           0.03125000
 -0.45344985    0.00000000    0.00000000           0.03125000
  0.00000000   -0.78539819    0.00000000           0.03125000
  0.45344985   -1.57079637    0.00000000           0.03125000
  0.90689969   -2.35619450    0.00000000           0.03125000
  1.36034954   -3.14159274    0.00000000           0.03125000

The total energy vs. the lattice parameter is plotted here: