Test of constant pH in GB on HEWL &cntrl ig=49, nstlim =2500000 cut=30.0, scee=1.2, igb=2, saltcon=0.1, ntx=1, irest=0, ntb=0, ntpr=500, dt=0.002, nrespa=1, ntt=1, tempi=300.0, temp0 = 300., tautp=2.0, ntc=2, ntf=2, tol=0.000001, ntwr =500, ntwx=500, rgbmax=30.0 icnstph=1, ntcnstph=1, solvph=3.0 /