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: {{:energy_new.png|}} 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?**