Hi Carlos,
Thankyou for your response to my questions. I am still slightly
confused (its just not only sander) so I just wanted to clarify what
you have said. Sander should be able to run the simulation with
multiple solutes but it is unclear how meaningful the results will be?
Dr Geoffrey Wood
Ecole Polytechnique Fédérale de Lausanne
SB - ISIC - LCBC
BCH 4108
CH - 1015 Lausanne
On May 9, 2007, at 10:52 PM, Carlos Simmerling wrote:
> Hi Geoff, yes that's true, I think that it's not so much that
> sander will get confused as it might
> cause problems in the centering/imaging and possible inability to
> get a single set of
> coordinates with a complete solvent shell around multiple solutes.
> This isn't a problem in the
> fully solvated system during MD due to the periodicity, but the
> hybrid calculation
> is done without periodicity. As far as ions go, I think one needs
> to have the same
> caution as with explicit counterions and any implicit solvent-
> we're not sure how well
> they work or what the limitations are, so treat it cautiously and
> only try it after you're
> sure you understand what you are doing without them.
> carlos
>
> On 5/9/07, Geoff Wood <geoffrey.wood.epfl.ch> wrote:
> Hello Asim,
>
> Thank you very much for your suggestions they were very helpful. I
> have made sure that the topology and number of waters correspond to
> what sander is expecting. That being said, I haven't been able to
> make much progress. If I understand your email correctly then any
> attempt to run hybrid remd with counter-ions will cause sander to
> get confused as to what is solute and solvent? If this is the
> case, then would the same be true if I decided to run a hybrid remd
> run with more than one solute (say a dimer of two proteins)?
>
> Thanks in advance,
>
> Dr Geoffrey Wood
> Ecole Polytechnique Fédérale de Lausanne
> SB - ISIC - LCBC
> BCH 4108
> CH - 1015 Lausanne
>
>
>
>
> On May 9, 2007, at 9:07 PM, Asim Okur wrote:
>
>> Hi,
>>
>> Before running Hybrid Solvent REMD you should read the manual and the
>> article (Okur, Roe, Cui, Hornak and Simmerling, JCTC, 2007)
>> especially
>> the warnings in the manual (Page 168).
>>
>> Your hybrid topology file should have exactly the same number of
>> waters as the reduced system generated by sander. Use of counterions
>> has not been implemented/tested with hybrid remd and should not be
>> used.
>>
>> Also, I see in your GB calculations (mdin.rep01.strip) you set nstlim
>> = 1000. You should not do any dynamics during the GB step. Just
>> single
>> step energy evaluation is needed. You can see examples of input files
>> in the remd and hybrid remd test cases in amber9.
>>
>> I hope this helps,
>>
>> Asim
>>
>> --
>> Asim Okur, Ph.D.
>> Stony Brook University
>> Chemistry Department
>> Stony Brook, NY 11733
>> (631) 632 1560
>>
>>
>> On 5/9/07, Geoff Wood < geoffrey.wood.epfl.ch> wrote:
>>>
>>>
>>>
>>> Slightly from first email but essentially the same:
>>>
>>>
>>> To whom it may concern,
>>>
>>> I am attempting to run hybrid remd simulations with amber 9 but I
>>> find that
>>> I cannot get them started. I am probably making a simple
>>> mistake in the
>>> specification of the file names, any help would be much appreciated.
>>>
>>> The error I am getting is the following:
>>>
>>> --------------------------------------------------------------------
>>> ------------
>>> 3. ATOMIC COORDINATES AND VELOCITIES
>>> --------------------------------------------------------------------
>>> ------------
>>>
>>>
>>> FATAL: NATOM mismatch in coord and topology files
>>>
>>>
>>> This error appears in the stripped output file (i.e. a file
>>> called something
>>> like mdout.rep01.strip)
>>> In the full output file it looks as if the calculation has
>>> finished (the
>>> file is called mdout.rep01) i.e.
>>>
>>> Exiting runmd after getting initial energies for REMD 0
>>> wrapping first mol.: 1.009557807795775E-014 68.4142020000000
>>> 96.4591000000000
>>>
>>> --------------------------------------------------------------------
>>> ------------
>>> 5. TIMINGS
>>> --------------------------------------------------------------------
>>> ------------
>>>
>>> |>>>>>>>>PROFILE of Average TIMES>>>>>>>>>
>>>
>>>
>>>
>>>
>>>
>>> The groupfile looks like
>>>
>>> -O -i mdin.rep01 -o mdout.rep01 -p prm -c inpcrd.rep01 -r
>>> restrt.rep01 -x
>>> mdcrd.rep01 -inf mdinfo.rep01
>>> .
>>> .
>>> .
>>> .
>>>
>>> The input files look like:
>>>
>>> Full box (mdin.rep01)
>>>
>>> comment
>>> &cntrl
>>> imin = 0, irest = 1, ntx = 2,
>>> ntb = 2, pres0 = 1.0, ntp = 1,
>>> taup = 2.0,
>>> cut = 10, ntr = 0,
>>> ntc = 2, ntf = 2,
>>> tempi = 0.0, temp0 = 300.0,
>>> ntt = 3, gamma_ln = 1.0,
>>> repcrd=0, numexchg=40, numwatkeep=350,
>>> nstlim = 1000, dt = 0.002,
>>> ntpr = 100, ntwx = 100, ntwr = 1000
>>> &end
>>> &ewald
>>> &end
>>>
>>> Reduced number of waters ( mdin.rep01.strip)
>>>
>>> comment
>>> &cntrl
>>> imin = 0, irest = 1, ntx = 2,
>>> ntb = 0,
>>> igb=1,
>>> cut = 999, ntr = 0,
>>> ntc = 2, ntf = 2,
>>> tempi = 0.0, temp0 = 366.0,
>>> ntt = 3, gamma_ln = 1.0,
>>> repcrd=0, numexchg=40, numwatkeep=350,
>>> nstlim = 1000, dt = 0.002,
>>> ntpr = 100, ntwx = 100, ntwr = 1000
>>> /
>>>
>>>
>>> I have placed both the full parm file (prm) and reduced parm file
>>> (prm.strip) in the same directory. For the stripped parm I have
>>> tried with
>>> and without the counter ions that are present in the full
>>> calculation. I
>>> think it is preferable to omit them in a GB energy evaluation.
>>> The stripped
>>> parm was made using leap and a pdb that ptraj generated from a
>>> short md run
>>> involving the full system.
>>>
>>> The input coordinates are for the full system ( from a short md
>>> run for
>>> equilibration) and are placed in the same directory as
>>> inpcrd.rep01 etc.
>>>
>>> Thanks in advance,
>>>
>>>
>>> Dr Geoffrey Wood
>>> Ecole Polytechnique Fédérale de Lausanne
>>> SB - ISIC - LCBC
>>> BCH 4108
>>> CH - 1015 Lausanne
>>>
>>>
>>>
>>>
>>>
>>>
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Received on Sun May 13 2007 - 06:07:14 PDT
