(* Ar atom Kimball, Ne-center, outer-sp-spheres 21.12.2011 *)
Clear[k1,k2,k3,sig1,sig2,sig3,c,z,R1,R2,R3,S2];
c = {k1 -> 1.0, k2 -> 1.0, k3 -> 1.0, sig1 -> 0.3, sig2 -> 0.3, sig3 -> 0.3};

(* Ne shell *)
T = 2.25*k1/R1^2+9.*k2/R2^2 /. c;
ad = Sqrt[3./8.]; 
Vee=3.0*sig1/R1+12.*sig2/R2+16/(R1+R2)+24*ad/(R1+R2) /. c;
Vne=-3.0*z/R1-8.*z/(R1+R2);
S2 = R2*4^(1/3);

(* Ar shell *)
T = T + 9.*k3/R3^2 /. c;
Vee = Vee+12.*sig3/R3+80./(S2+R3)+24.*ad/(S2+R3) /. c;
Vne = Vne-8.35*z/(S2+R3);
S3 = R3*4^(1/3);

func = T + Vee + Vne;

t = Table[FindMinimum[func, {R1,0.07}, {R2,0.27}, {R3,0.9},{Method -> Automatic}, {MaxIterations -> 500}], {z,18,26}]

Table[N[Vne /. c /. t[[{z-17},2]],10], {z,18,26}]
Table[N[Vee /. c /. t[[{z-17},2]],10], {z,18,26}]
Table[N[-(Vee+Vne)/T /. c /. t[[{z-17},2]],10], {z,18,26}]
Table[N[(S2+R3) /. c /. t[[{z-17},2]],10], {z,18,26}]