simplify code

Author: brucefan1983

src/main_nep/fitness.cu

@@ -20,7 +20,6 @@ Get the fitness
 #include "fitness.cuh"
 #include "nep.cuh"
 #include "nep_charge.cuh"
-#include "nep_charge_vdw.cuh"
 #include "tnep.cuh"
 #include "parameters.cuh"
 #include "structure.cuh"
@@ -128,12 +127,9 @@ Fitness::Fitness(Parameters& para)
     potential.reset(
       new TNEP(para, N, N_times_max_NN_radial, N_times_max_NN_angular, para.version, deviceCount));
   } else {
-    if (para.charge_mode >= 1 && para.charge_mode <= 3) {
+    if (para.charge_mode >= 1 && para.charge_mode <= 4) {
       potential.reset(
         new NEP_Charge(para, N, Nc, N_times_max_NN_radial, N_times_max_NN_angular, para.version, deviceCount));
-    } else if (para.charge_mode == 4) {
-      potential.reset(
-        new NEP_ChargeVdW(para, N, Nc, N_times_max_NN_radial, N_times_max_NN_angular, para.version, deviceCount));
     } else {
       potential.reset(
         new NEP(para, N, N_times_max_NN_radial, N_times_max_NN_angular, para.version, deviceCount));