Dear All,
I am doing replica exchange method using implicit solvent, looking into the results summary.TEMP created by using reminfo file i found that the temperature is fluctuating a lot even though i am using langevin thermostat.I started from temp range 273K to 373K but in the output file there are temperature 402 K and above also.
Method i followed is as under with the input files:
1) minimized the linear structure generated by Xleap: input file:
Stage 1 - minimisation of am15-42 in implicit solvent
&cntrl
imin=1, maxcyc=5000, ncyc=2500,
cut=999., rgbmax=999.,igb=1, ntb=0,
ntpr=100
/
2) heated the system for different temperatures which could act as the starting conformations for the Replica exchange method. input file was (only temp different in files):
am15: 100ps MD in implicit solvent
&cntrl
imin = 0,
ntb = 0, igb = 1,
cut = 10,
tempi = 373.715, temp0 = 373.715,
ntt = 3, gamma_ln = 1.0,
nstlim = 50000, dt = 0.002,
ntpr = 50, ntwx = 50, ntwr = 50
/
3) REMD using the reference rst from from the previous step at different temp
input file (different temp for different replicas):
&cntrl
imin = 0, nstlim = 100, dt = 0.002,
ntx = 5, tempi = 360.893,temp0 =360.893,
ntt = 3, tol = 0.0000001,
ntc = 2, ntf = 1, ntb =0,
ntwx = 5, ntwe = 0, ntwr = 5, ntpr = 5,
cut =10.0, scee = 1.2, ibelly =0,
ntr = 0, gamma_ln = 1.0,offset = 0.09
nscm = 500, igb = 1,
irest = 1,numexchg = 50000, repcrd = 0,ntave = 0,
/
System is running fine with showing exchanges in the log file that has been created, but if i extract output for the various repinfo file created for different replicas, i found strange fluctuation in temp which are not the range given.
Will anybody see error in my steps and my input file.
Suggestion are welcomed.
Regards
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Received on Sun Jul 22 2007 - 06:07:42 PDT
