The ABINIT Users Mailing List ( CLOSED )

[ngalamba@cii.fc.ul.pt]

Dear ABINIT users

I am trying to use ABINIT to carry molecular dynamics simulations (N,V,E) 
(IONMVOV 6) of simple ionic melts (e.g. NaCl).
Because it is hard to get a complete simulation on a single run without 
computers crashing for some reason I have been trying to divide my production 
runs in several stages that I therefore need to link.

To link the partial simulations (say a 100 time-steps each with a time-step 
of 5 fento seconds) I use the variable IRDWFK 1 to use the wavefunction from 
the previous partial run and update the positions and velocities in the new 
input file. ABINIT tells me that the file is good for restarting the 
simulation and takes it from there.

The "problem" is that the first time (MD step 1 not 0) ABINIT updates the 
positions and velocities using the Verlet algorithm it only gives me the 
first 6 digits of positions and velocities equal to those I would obtain if I 
had continued the simulation on a single run. Then as more and more 
integrations are performed the positions and velocities start to get more and 
more different from those I would obtain in a single run.

Is there any way of restarting a MD calculation in a such a way that the 
results are identical whether we do it in several stages using the _WFK files 
as input or in just a single run?

I would be highly appreciated if anyone could give some hint on this type of 
calculation as I am new to ABINIT and also to Hellman-Feynamnn MD.

Thanks in advance.

Nuno Galamba