Re: [AMBER] confusions about some thermodynamic properties of TIP3P water

From: zhouhaibin2008.ok <>
Date: Mon, 18 Jul 2011 22:01:52 +0800 (CST)

I simulated the thermodynamic properties of 612 TIP3P water model. Here is the input file when I run production MD.
I have calculated some properties :the Isobaric heat capacity is 18.24(kcal/mol), the Isothermal compressibility is 93(10^-6/atm), the thermal expansion coefficient is 81(10^-5/k). It is these three results that confused me. Please tell me are they reasonable?
Thank you

At 2011-07-18 17:02:01£¬ wrote:

>> I used TIP3P water model to simulate some properties for liquid water at
>> 300k and 1atm.The result are based on averages covering 2ns.But the
>> thermodynamic results, for example the isothermal compressibilities and
>> isobaric heat capacity, are different from the calculated properties
>Did you exactly replicate the simulations in your reference paper? Changes
>in simulation length, cutoffs, electrostatics model, time-steps, etc. can
>strongly influence your results. You do not give details about your
>simulations and do not say how big the differences are that you see, so
>its hard to judge if the results are reasonable.
>Note that MD simulations (especially long ones) are not exactly
>replicable. Due to round-off differences, trajectories diverge and you may
>see slightly different results when running even the same simulation setup
>> pointed by some paper using the same TIP3P water model .Please tell me
>> what is the actual result or the range of the properties.
>Im not sure there is an 'actual' result, the behaviour of a water model
>will depend on the physical parameters used in the simulation.
>Kind Regards,
>Dr. Thomas Steinbrecher
>formerly at the
>BioMaps Institute
>Rutgers University
>610 Taylor Rd.
>Piscataway, NJ 08854
>AMBER mailing list
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Received on Mon Jul 18 2011 - 07:30:03 PDT
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