(* H2+ with parameters  22.10.2012 ES *)
Clear[sig,k,R,r,tot,d];
sig=0.00; k=1.21;

Etot = k 9/(8 R^2) + 1/(2 r)+3 sig/R-(2/R)*(3/2 - (1/2)*(r/R)^2);

t=FindMinimum[Etot, {R, 1.5}, {r,1.0}]
d=2*r*0.529177 /. t[[2,2]]
t[[1]]