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linxi1454

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[交流] Steps to Perform a Simulation 分子模拟步骤

Below is presented a generalised procedure for performing a simulation. The
exact steps and processes involved will vary depending on exactly what is being
attempted. Use as a general guide only!

1> Clearly identify the property / phenomena of interest to be studied by performing the simulation.

2>Select the appropriate tools to be able to perform the simulation and observe the property / phenomena of interest. It is important to read and familiarise
yourself with publications by other researchers on similar systems. Tools include:
- software to perform the simulation with, consideration of force field may
influence this decision.
- force field which describes how the atoms / particles within the system interact with each other. Select one that is appropriate for the system being studied and the property / phenomena of interest. Very important and non-trivial step!

3>Obtain / generate the initial coordinate file for each molecule to be placed
within the system.

4>Generate the raw starting structure for the system by placing the molecules
within the coordinate file as appropriate. Molecules may be specifically placed or arranged randomly.

5>Obtain / generate the topology file for the system, using (for example)
pdb2gmx, PRODRG or your favourite text editor in concert with chapter 5 of the GROMACS Manual.

6>Describe a simulation box (e.g. using editconf) whose size is appropriate for
the eventual density you would like, fill it with solvent (e.g. using genbox), and
add any counter-ions needed to neutralize the system (e.g. using grompp and
genion). In these steps you may need to edit your topology file to stay current
with your coordinate file.

7>Run an energy minimisation simulation on the system (using grompp and
mdrun). This is required to sort out any bad starting structures caused during
generation of the system, which may cause the production simulation to crash.

8>Select the appropriate simulation parameters for the equilibration simulation (defined in .mdp file). You need to be consistent with how force field was
derived. You may need to simulate at NVT with position restraints on your
solvent and/or solute to get the T almost right, then relax to NPT to fix the
density, then move further (if needed) to reach your production simulation
ensemble (e.g. NVT, NVE).

9>Run the equilibration simulation for sufficient time so that the system relaxes sufficiently to allow the production run to be commenced (using grompp and
mdrun, then g_energy and trajectory visualisation tools).

10>Select the appropriate simulation parameters for the production simulation (defined in .mdp file), in particular be careful not to re-generate the velocities.
You still need to be consistent with how the force field was derived and how to
measure the property / phenomena of interest.

11>Run the production simulation for sufficient time so that property / pheno-
mena of interest can be observed in required detail (using grompp/tpbconv and mdrun).

12>Analyse / visualise the resulting trajectory and data files to obtain information on the property / phenomena of interest.

本帖转自分子动力学模拟论坛:http://simulation.5d6d.com/home.php

[ Last edited by linxi1454 on 2008-3-20 at 20:50 ]
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