Talk:Mod:Hunt Research Group/Equilibraton

This needs to be setup correctly!!!

2. run NPT

-don't want the dynamic properties here because of the forces applied to keep the pressure constant, these directly effect the dynamic properties, use the NVT for properties.

starting from a roughly pre-equilibrated trajectory (NPT done) this is your NVT simulation

-NVE is possible, but NVT conserves the temp and will correspond to experimental const temp timestep given in ps, step size 1fs is standard (with H's) a good equilibration for pure water is 200-500ps but for ions in water, or ILs you need 2000-5000ps

want to check the temperature, total energy and maybe pressure the temperature should oscillate +/- 5-10K around the set target value the total energy should be conserved, you should see no drift after initial equilibration the pressure can fluctuate widely

it is possible for a state to be reached where the temp increases continuously, or the energy fails to level off and decreases continuously this is bad. You will have errors in your input.

you can eyeball the numbers but it is best to visualise these you can visualise using the dlpoly gui (part of the dlpoly source-code) to use this on the cluster exporting your display you need to login with -X option eg ssh -X username:hpc_path then load the gui, type

 > module load dl_poly/2.19 (return)
> gui (return)

now to visualise the temp and E

goto ANALYSIS

choose TEMP

then RUN