Copper has a fcc crystal structure. The unit cell is containing only one atom, thus the Cu_bulk.bas file contains only one atom:

   1
29    0.00000    0.00000    0.00000

The unit cell prepared, so [1,1,0] crystallography axis is equal to x axis is written in the Cu_bulk.lvs:

 0.70711    0.00000    0.00000
 0.35355    0.61237    0.00000
 0.35355    0.20412    0.57735

And the 8x8x8 Monkhorst-Pack grid is via Oh symmetry of the cell reduced to the 105 k-points, which are in the Cu_bulk.kpts:

       105
 -3.70238566   -2.13762188   -1.51153386           0.00925926
 -3.70238566   -2.13762188    0.30226633           0.00925926
 -3.70238566   -2.13762188    2.11606646           0.00925926
 -3.70238566   -2.13762188    3.92986679           0.00925926
  5.18333989    2.99267047   -1.51145290           0.00925926
 -3.70238566   -2.13762188   -3.32533396           0.00925926
 -3.70238566   -0.42754856   -2.11612415           0.00925926
 -3.70238566   -0.42754856   -0.30232388           0.00925926
 -3.70238566   -0.42754856    1.51147640           0.00925926
 -3.70238566   -0.42754856    3.32527661           0.00925926
 -3.70238566   -0.42754856    5.13907671           0.00925926
 -3.70238566   -0.42754856   -3.92992438           0.00925926
 -3.70238566    1.28252470   -2.72071433           0.00925926
 -3.70238566    1.28252470   -0.90691411           0.00925926
 -3.70238566    1.28252470    0.90688616           0.00925926
 -3.70238566    1.28252470    2.72068644           0.00925926
 -3.70238566    1.28252470    4.53448677           0.00925926
 -3.70238566    1.28252470   -4.53451479           0.00925926
 -3.70238566    2.99259806   -3.32530451           0.00925926
 -3.70238566    2.99259806   -1.51150429           0.00925926
 -3.70238566    2.99259806    0.30229595           0.00925926
 -3.70238566    2.99259806    2.11609626           0.00925926
  5.18333989   -2.13754919    0.30231756           0.00925926
  5.18333989   -2.13754919    2.11611790           0.00925926
  5.18333989   -0.42747620    3.32532794           0.00925926
 -3.70238566    4.70267105   -2.11609459           0.00925926
 -3.70238566    4.70267105   -0.30229425           0.00925926
  5.18333989   -0.42747620   -2.11607283           0.00925926
  5.18333989   -0.42747620   -0.30227261           0.00925926
  5.18333989   -0.42747620    1.51152748           0.00925926
 -3.70238566   -3.84769508   -0.90694363           0.00925926
 -3.70238566   -3.84769508    0.90685647           0.00925926
 -3.70238566   -3.84769508    2.72065674           0.00925926
  5.18333989    1.28259727   -2.72066301           0.00925926
  5.18333989    1.28259727   -0.90686279           0.00925926
  5.18333989    1.28259727    0.90693754           0.00925926
 -2.22143149   -2.99264646   -2.11613035           0.00925926
 -2.22143149   -2.99264646   -0.30233014           0.00925926
 -2.22143149   -2.99264646    1.51147008           0.00925926
 -2.22143149   -2.99264646    3.32527041           0.00925926
 -2.22143149   -2.99264646    5.13907051           0.00925926
 -2.22143149   -2.99264646   -3.92993057           0.00925926
 -2.22143149   -1.28257310   -2.72072053           0.00925926
 -2.22143149   -1.28257310   -0.90692037           0.00925926
 -2.22143149   -1.28257310    0.90687990           0.00925926
 -2.22143149   -1.28257310    2.72068024           0.00925926
 -2.22143149   -1.28257310    4.53448057           0.00925926
 -2.22143149   -1.28257310   -4.53452099           0.00925926
 -2.22143149    0.42750019   -3.32531071           0.00925926
 -2.22143149    0.42750019   -1.51151061           0.00925926
 -2.22143149    0.42750019    0.30228969           0.00925926
 -2.22143149    0.42750019    2.11608982           0.00925926
 -2.22143149    0.42750019    3.92989016           0.00925926
 -2.22143149    0.42750019   -5.13911093           0.00925926
 -2.22143149    2.13757348   -3.92990088           0.00925926
 -2.22143149    2.13757348   -2.11610079           0.00925926
 -2.22143149    2.13757348   -0.30230051           0.00925926
 -2.22143149    2.13757348    1.51149976           0.00925926
 -2.22143149    2.13757348    3.32529998           0.00925926
 -2.22143149    2.13757348    5.13910007           0.00925926
 -2.22143149    3.84764671   -4.53449106           0.00925926
 -2.22143149    3.84764671   -2.72069097           0.00925926
 -2.22143149    3.84764671   -0.90689075           0.00925926
 -2.22143149    3.84764671    0.90690953           0.00925926
 -2.22143149    3.84764671    2.72070980           0.00925926
 -2.22143149    3.84764671    4.53451014           0.00925926
 -2.22143149   -4.70271942   -1.51154024           0.00925926
 -2.22143149   -4.70271942    0.30226009           0.00925926
 -2.22143149   -4.70271942    2.11606031           0.00925926
 -2.22143149    5.55772018    0.30231929           0.00925926
 -2.22143149    5.55772018    2.11611962           0.00925926
 -2.22143149   -4.70271942   -3.32534047           0.00925926
 -0.74047714   -3.84767079   -2.72072673           0.00925926
 -0.74047714   -3.84767079   -0.90692663           0.00925926
 -0.74047714   -3.84767079    0.90687364           0.00925926
 -0.74047714   -3.84767079    2.72067380           0.00925926
 -0.74047714   -3.84767079    4.53447390           0.00925926
 -0.74047714   -3.84767079   -4.53452719           0.00925926
 -0.74047714   -2.13759756   -3.32531714           0.00925926
 -0.74047714   -2.13759756   -1.51151681           0.00925926
 -0.74047714   -2.13759756    0.30228344           0.00925926
 -0.74047714   -2.13759756    2.11608362           0.00925926
 -0.74047714   -2.13759756    3.92988396           0.00925926
 -0.74047714   -2.13759756   -5.13911713           0.00925926
 -0.74047714   -0.42752436   -3.92990732           0.00925926
 -0.74047714   -0.42752436   -2.11610699           0.00925926
 -0.74047714   -0.42752436   -0.30230677           0.00925926
 -0.74047714   -0.42752436    1.51149344           0.00925926
 -0.74047714   -0.42752436    3.32529378           0.00925926
 -0.74047714   -0.42752436    5.13909388           0.00925926
 -0.74047714    1.28254890   -4.53449726           0.01851852
 -0.74047714    1.28254890   -2.72069716           0.01851852
 -0.74047714    1.28254890   -0.90689701           0.01851852
 -0.74047714    2.99262214   -5.13908768           0.00925926
 -0.74047714    2.99262214   -3.32528734           0.00925926
 -0.74047714    2.99262214   -1.51148725           0.00925926
 -0.74047714    2.99262214    0.30231303           0.00925926
 -0.74047714    2.99262214    2.11611319           0.00925926
 -0.74047714    2.99262214    3.92991352           0.00925926
 -0.74047714   -5.55774423   -2.11613686           0.00925926
 -0.74047714   -5.55774423   -0.30233628           0.00925926
 -0.74047714    4.70269537   -2.11607742           0.00925926
 -0.74047714    4.70269537   -0.30227718           0.00925926
 -0.74047714    4.70269537    1.51152313           0.00925926
 -0.74047714    4.70269537    3.32532334           0.00925926

A fireball.sample file, which will be used as a template to the fireball.in looks like this:

&OPTION
basisfile = Cu_bulk.bas
lvsfile = Cu_bulk.lvs
kptpreference = Cu_bulk.kpts
nstepf = 1
rescal = AAA
&END

And the shell script executing all the stuff (changing rescaling factor, running fireball in runTG.com, saving energy to energy.dat, …) called fireball.sh is written here:

alat="3.59 3.60 3.61 3.62 3.63 3.64 3.65 3.66 3.67 3.68 3.69 3.70 3.71 3.72 3.73 3.74 3.75 3.76 3.77 3.78 3.79 3.80"
for i in $alat;
do
 echo $i
 mkdir $i
 lattice="`echo $i`";
 sed "s/AAA/$lattice/g"  fireball.sample > fireball.in;
 ./runTG.com > a-$i.out
 en=`grep "etot/atom" a-$i.out | cut -b50-65`
 echo $i $en >> energy.dat
 mv CHARGES $i/
 mv a-$i.out $i/
done

Now the energy is written in the energy.dat file and can be plotted e.g. via gnuplot:

plot 'energy.dat' w lp

And the results are shown:

Thus the lattice constant is: 3.66 Angstrom (3.614 is the experimental value).

The lattice parameter and the k-points from the Si lattice optimization can be used as well. Did, the results changed somehow?