#!/usr/bin/env gnuplot ## HARTREE_IN_EV = 27.21138386 BOHR = 0.5291772083 set encoding iso_8859_1 set terminal postscript portrait enhanced "Times-Roman" color 24 set output "perovskite-B1112.eps" set multiplot Etot(x) = B0*x/(B0p*(B0p-1.0)) *(B0p*(1.0-V0/x)+(V0/x)**B0p-1.0)+Emin # initial values B0 = 1.2 B0p = 4.4 V0 = 64.0 Emin = -3587.0 fit Etot(x) 'perovskite-B1112.dat1' using (($2*BOHR)**3):($7*HARTREE_IN_EV) via B0, B0p, V0, Emin Etot11(x) = B11/2*((x-a0)/a0)**2 + Emin11 # initial values a0 = 7.44 # [Bohr] B11 = 130.0 # [eV] Emin11 = -3587.0 # [eV] fit Etot11(x) 'perovskite-B1112.dat2' using ($4):($7*HARTREE_IN_EV) via a0,B11,Emin11 set size 1.0,0.5 set format y "%.3f" set ylabel "{/Times-Italic E}_{tot}-{/Times-Italic E}_0 [eV]" set origin 0.0,0.5 set yrange [-0.01:0.05] set xlabel "{/Times-Italic V} [\305^3]" set xtics 1 plot 'perovskite-B1112.dat1' using (($2*BOHR)**3):($7*HARTREE_IN_EV-Emin) t 'calculated data' w p pt 1 ps 2 lw 3,\ Etot(x)-Emin t 'equation of state' w l lt 1 lw 3 set origin 0.0,0.0 set yrange [-0.005:0.020] set xlabel "{/Times-Italic e_{xx}}" set xtics 0.01 plot 'perovskite-B1112.dat2' using (($4-a0)/a0):($7*HARTREE_IN_EV-Emin11) t 'calculated data' w p lt 2 pt 2 ps 2 lw 3,\ B11/2*x**2 t 'quadratic fitting' w l lt 2 lw 3 # B11 and B12 print 'DATASET 1 -- 9' a0_Angstrom = V0**(1.0/3) print 'a0 = ', a0_Angstrom/BOHR, ' [Bohr] = ', a0_Angstrom, ' [Angstrom]' print 'Emin = ', Emin, ' [eV]' print 'B = ', B0*160.22, ' [GPa]' print 'DATASET 10 -- 19' print 'a0 = ', a0, ' [Bohr] = ', a0*BOHR, ' [Angstrom]' print 'Emin = ', Emin11, ' [eV]' print 'B11 = ', B11, ' [eV]' C11 = B11 / a0_Angstrom**3 * 160.22 print 'C11 = ', C11, ' [GPa]' print 'Compute B12' B12 = (3*B0*a0_Angstrom**3-B11)/2 print 'B12 = ', B12, ' [eV]' C12 = B12 / a0_Angstrom**3 * 160.22 print 'C12 = ', C12, ' [GPa]' #Local variables: # compile-command: "gnuplot perovskite-B1112.gp" #End: