[gpaw-users] start a calculation using results from different software

[Nichols A. Romero]

This would be hard to do. But if you are using the RMM-DIIS eigensolver, GPAW
already uses an LCAO initialization for the real-space grid code. So I don't
think that DFTB buys you any significant computational savings.

Nichols A. Romero, Ph.D.
Argonne Leadership Computing Facility
Argonne National Laboratory
Building 240 Room 2-127
9700 South Cass Avenue
Argonne, IL 60490
(630) 252-3441


----- Original Message -----
From: "Alex Eftimiades" <alexeftimiades at gmail.com>
To: "Nichols A. Romero" <naromero at alcf.anl.gov>
Cc: "gpaw-users" <gpaw-users at listserv.fysik.dtu.dk>
Sent: Friday, November 18, 2011 4:30:36 PM
Subject: Re: [gpaw-users] start a calculation using results from different software

Although I would not have used the word "re-use" I suppose I would say 2. 

I would like to calculate wavefunctions, electron density, etc using DFTB, save the results, and then start a gpaw calculation with those results as its "initial guess." 

Alex 


On Fri, Nov 18, 2011 at 11:15 AM, Nichols A. Romero < naromero at alcf.anl.gov > wrote: 


Alex, 

Do you mean: 
1. How to re-use the calculator object between a DFTB or GPAW? 
2. How to re-use a DFTB calculation to start/continue a GPAW calculation? 

Nichols A. Romero, Ph.D. 
Argonne Leadership Computing Facility 
Argonne National Laboratory 
Building 240 Room 2-127 
9700 South Cass Avenue 
Argonne, IL 60490 
(630) 252-3441 





----- Original Message ----- 
From: "Alex Eftimiades" < alexeftimiades at gmail.com > 
To: "gpaw-users" < gpaw-users at listserv.fysik.dtu.dk > 
Sent: Thursday, November 17, 2011 5:45:15 PM 
Subject: [gpaw-users] start a calculation using results from different software 


I have been looking into hotbit, an ase compatible DFTB software, and I was wondering if there might be a way to start a calculation with hotbit and hand over the results to gpaw. I would like to be able to do something along the lines of: 


gpaw_calculator=GPAW{...} 
hotbit_calculator=Hotbit{...} 
atoms=.... 
atoms.set_calculator(hotbit_calculator) 
atoms.get_potential_energy() 
gpaw_calculator.set_density_matrix(hotbit_calculator.get_density_matrix()) 
gpaw_calculator.set_grid_spacing(hotbit.get_grid_spacing()) 
...... 
atoms.set_calculator(gpaw_calculator) 
atoms.get_potential_energy() 


This is of course neither the correct syntax for gpaw nor hotbit, but I think it conveys the idea. 


What information would gpaw need to pickup where a calculator like hotbit left off? How might I set those parameters with gpaw? 


For more on what information hotbit can do see 
https://svn.cc.jyu.fi/srv/svn/hotbit/trunk/hotbit/aseinterface.py 




I am assuming this cannot possibly be as simple as resetting the calculator after hotbit (I was under the impression ase mainly stores the locations of atoms and the dimensions of the unit cell--not the results of calculations.) I would not be surprised to find that there is no easy way to do this and that it is probably worth the effort. However, I thought it would be worth asking the question since it would be a very useful procedure. 


Thanks, 
Alex 
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