T = 2.25/Q^2 + 2.25*4/P^2;
b = (r^2 + R^2 + 2*R*(r^2 - a^2/4)^(1/2))^(1/
              2);
Vee = 
        0.9/P + 0.9/Q + 
          4*((3/2) - (1/2)*(R/P)^2 - (3/10)*(Q/P)^2)/
              P;
Vnn = 1/a + 2*Z/b;
Vne = -3*Z/Q - 4/b - 
          4*((3/2) - (1/2)*(r/P)^2)/P - 
          2*Z*((3/2) - (1/2)*(R/P)^2)/
              P;
Z = 3.0;
func = T + Vne + Vee + Vnn;
FindMinimum[
      func, {P, 4}, {Q, 0.6}, {R, 1.0}, {r, 1.0}, {a, 
        1.0}]