#!/usr/bin/gnuplot f(x)=k*(x-x0)*(x-x0)+e0 # definition of the function to be fitted delta = 0.002 # e0=0.007720330647107 # initial value of e0 k = 500 # initial value of k x0=1 # initial value of x0 #a0 = 1.3327436840 # set xlabel 'd (Angstrom)' # label of the x-axis set ylabel 'E (kcal/mol)' # label of the y-axis set title "c2h2 triple bond" # main title fit f(x) 'curve.a.c2h2' u ($1):(($2)*627) via k,x0,e0 # fitting procedure # ^ function to be fitted # ^ take data from the file curve.a.c2h2 # and use the first column as X and the second one # ax Y (all values of the second column are multiplied by 627. 1 Hartree = 627 kcal/mol) # ^ k, x0, e0 - are parameters to be adjusted plot 'curve.amber.c2h2' u ($1):(($2)*627)-e0 t 'computed AMBER' w lp lw 2 ps 2 pt 7, f(x)-e0 t 'k*(x-x0)^2' w l lw 2 # ^ take data for the first plot from the file curve.a.c2h2 # ^ use the firts column as X and the second as Y # ^ title of the first plot: computed AMBER # ^ draw points and lines # ^ line width = 2 # ^ point size = 2 # ^ point type = 7 # ^ plot function f(x)-e0 # ^ title of the second plot: k*(x-x0)^2 # ^ draw only line # ^ line width = 2 pause mouse # exit by right-clicking on the plot window # EOF