contour.gp

set dgrid3d 30,30
set hidden3d 
set cntrparam levels incremental 1.2,0.1,1.8
set contour
set view 0,0
unset surface
set format z ""
set key outside
splot "chemeq.txt" lw 4 title "surface density"
set xlabel "{/Symbol s}/R" offset 4.,0.8 font "Helvetica, 20"
set ylabel "C_{B}{/Symbol s}^{3}" offset 1.8,2.5 font "Helvetica, 20"

set terminal postscript eps enhanced color solid
set output "chemeq.eps"
replot