MD determin the structure

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vasp16888
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MD determin the structure

#1 Post by vasp16888 » Wed Aug 11, 2010 8:49 am

Dear vasp users:
I am MD learner, and I wanna to use MD simulation to determin the structure of Our system(at least 128 atoms, or 432 atoms or more).
I read mannual, the MD parameters it suggests are:
==================
ENCUT = 150 eV ! energy cutoff (opt)
IALGO = 48 ! RMM-DIIS algorithm for electrons
LREAL = A ! evaluate projection operators in real space
NELMIN = 4 ! do a minimum of four electronic steps
BMIX = 2.0 ! mixing parameter
MAXMIX = 50 ! keep dielectric function between ionic movements
Ionic Relaxation
ISYM = 0 ! switch of symmetry
NSW = 100 ! number of steps for IOM
NBLOCK = 1 ; KBLOCK = 100
SMASS = 2.0 ! Nose mass-parameter (am)
POTIM = 3.00 ! time-step for ion-motion
TEBEG = 573 ! temperature
PC-function
APACO = 10.0 ! distance for P.C.
===============

Since i wanna determin the structure, I have to simulate the experimental process by MD, which means I should simulate increasing temperature from 0k to above the melting point(say 2000k), and then cool the system to 0k with a certain cooling rate.

I don't think the parameters above can simulate these two process(the heating process and cooling process)

So my questions are:
How do set the parameters to simulate this two process ?

Thanks a lot:)

<span class='smallblacktext'>[ Edited ]</span>
Last edited by vasp16888 on Wed Aug 11, 2010 8:49 am, edited 1 time in total.
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AB INITIO STUDY OF MAGNETIC MATERIALS
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MD determin the structure

#2 Post by admin » Thu Aug 26, 2010 2:32 pm

if you want to determin the DFT ground state structure, please use IBRION 1 (if you start close to the minimum already), 2 or 3.
If you really want to do simulated annealing, please set TEBEG and TEEND
Last edited by admin on Thu Aug 26, 2010 2:32 pm, edited 1 time in total.

vasp16888
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Posts: 44
Joined: Fri Apr 23, 2010 3:09 am

MD determin the structure

#3 Post by vasp16888 » Mon Aug 30, 2010 8:59 am

[quote="red"]So please give me some suggestion about how to improve the speed of MD simulation( I know for ab initio MD, the speed is way much slower than classical MD). Any suggestions about improving the speed of MD will be greatly appreciated:)[/color]

Thanks in advance!
Last edited by vasp16888 on Mon Aug 30, 2010 8:59 am, edited 1 time in total.
[align=center]
AB INITIO STUDY OF MAGNETIC MATERIALS
[/align]

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