Thank you very much for your reply.
yes, I'm sure using the same Amber binary, the same machine, the same number of CPU and comparing the same time interval. The results shock me, so I have checked everything that may affect the simulation.
>writing every 4fs is very often, and would
>probably give very laerge output files for a simulatino long enough to lose
>the XRD structure
what is the extrat meaning of this? Do you mean that writing the coordinates too often is equil to run MD simulation for a long time that may cause to lose XRD structure.
Thanks in advance.
Jianing
ÔÚ2010-04-12 19:09:45£¬"Carlos Simmerling" <carlos.simmerling.gmail.com> дµÀ£º
>the frequency of saving does not change the simulation. Are you sure that
>you ran them using the same Amber binary, on the same machine, using the
>same # of CPus, etc? many things can cause trajectories to diverge. Have you
>diffed the mndout files? are you sure that you are comparing the same time
>writing every 4fs is very often, and would
>probably give very laerge output files for a simulatino long enough to lose
>the XRD structure.
>
>2010/4/12 Nancy <song_jianing_hi.126.com>
>
>> Dear all,
>>
>> Recently I'm involved in performing MD simulation using AMBER.
>> At the beginning, the atom coordinates are saved to mdcrd file in every
>> 4fs(ntrw=2) time interval. Then for comparison, I save the atom coordinates
>> into mdcrd file every 10ps(ntrw=5000). Other parts of the two MD simulations
>> are all the same, and the only difference is the frequency of saving atom
>> coordinates. But the conformation between the two simulation give huge
>> difference. That from former protocol is far from the XRD structure at the
>> end. But that from the latter is similar to the XRD structure.
>>
>> This results shocks me, because the frequency of saving atom coordinates
>> shouldn't affect to MD simuation. I've checked all the input files, they are
>> the same, except options controlling the output such as 'ntwx'. The program
>> I use is sander in AMBER10, AMBER03 is the force field by which I've adopted
>> to perform simulation. My system is villin headpiece. Furthermore, explicit
>> solvation model TIP3P is used.
>>
>> The following is the two input file:
>>
>> ---The frequently-output input-------------
>> &cntrl
>> imin = 0,
>> irest = 1,
>> ntx = 5,
>> ntb = 1,
>> cut = 12.0,
>> ntc = 2,
>> ntf = 2,
>> tempi = 300.0,
>> temp0 = 300.0,
>> ntt = 3,
>> gamma_ln = 1.0,
>> nstlim = 5000, dt = 0.002
>> ntpr = 2, ntwx = 2, ntwr = 2
>> /
>> ----------------------------------------
>> ---The not-so-frequently-output input---
>> &cntrl
>> imin = 0,
>> irest = 1,
>> ntx = 5,
>> ntb = 1,
>> cut = 12.0,
>> ntc = 2,
>> ntf = 2,
>> tempi = 300.0,
>> temp0 = 300.0,
>> ntt = 3,
>> gamma_ln = 1.0,
>> nstlim = 2500000, dt = 0.002
>> ntpr = 5000, ntwx =5000 , ntwr = 5000
>> /
>> ----------------------------------------
>> can someone give me some advice and help me out of the trouble?
>> Thank you very much in advance.
>> Jianing
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>>
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Received on Mon Apr 12 2010 - 05:30:02 PDT
