func  =  
      2.25*1.0289716/P^2 + 2.25*1.23924503/Q^2 + 1/(P + Q + R) - 9/P - 
        2/(P + Q) - 3/Q + R^2/Q^3 + 3*0.29125954/Q + 
        3*0.27885572/P
FindMinimum[
      func, {P, 0.6}, {Q, 2.0}, {R, 0.5}]

func  =  
      2.25*1.02480344/P^2 + 2.25*1.23244364/Q^2 + 1/(P + Q + R) - 9/P - 
        2/(P + Q) - 3/Q + R^2/Q^3 + 3*0.28887416/Q + 
        3*0.27877144/P
FindMinimum[func, {P, 0.5}, {Q, 3.0}, {R, 0.5}]

func  =  
      2.25*1.02480344/P^2 + 1.125*1.23244364/Q^2 - 9/P - 1/(P + Q) + 
        3*0.27877144/P
FindMinimum[func, {P, 0.5}, {Q, 2.0}]

T = 2.25*k1/P^2 + 1.125*k2/Q^2;
Vne = -2*3*Z/(2*P) - 
          Z/(P + Q);
Vee = 2/(P + Q) + 3*s1/P;
func = T + Vne + Vee;
  
c = {k1  ->  1.02480344,  k2 ->  1.23244364,  
          s1 -> 0.27877144,  
          Z  ->  3.0};
func  =  func  /.  c
N[t = FindMinimum[func,  {P, 0.5}, {Q, 2.0  }], 
      10]
u  =  t[[2]];
  
N[Vne  /.  u  /.  c,  10]
  
N[Vee  /.  u  /. c,  10]
  
N[-(Vne + Vee)/T  /.  u  /.  c,  10]