model ASH to ASP for pKa calculation
 &cntrl
   nstlim =3000000, nscm=2000,
   ntx=5, irest=1, ntpr=1000,
   tempi=300.0, temp0=300.0, ntt=3, gamma_ln=5.0,
   ntb=0, igb=5, cut=999.0,
   dt=0.001, 
   ntc=2, ntf=2, 
   ntwr = 10000, ntwx=1000, ntave=1000
   icfe=1, clambda=0.11270,
 /