[gpaw-users] Benzene optimization 'Did not converge'

[Elsebeth Schröder]

> ________________________________________
> From: Elsebeth Schröder
> Sent: 07 December 2012 15:27
> To: qian li; gpaw-users at listserv.fysik.dtu.dk
> Cc: Elsebeth Schröder
> Subject: RE: [gpaw-users] Benzene optimization 'Did not converge'
> 
> Hi Qian Li,
> 
> I don't know about the KohnShamConvergeError, but once you figure that out, I suggest you lower the max force (0.01 eV/Å or lower) 
> because the energy minimum in sparse systems is shallow and the forces small. Also, and the grid spacing should be even smaller 
> than what you are testing now (I would use h=0.12 Å or > smaller). Finally, since the energy differences (like the binding energy) in 
> sparse matter systems are on the meV scale you will need to energy-converge your calculations better than the default gpaw settings. 
> For that you can use the
> convergence={'energy':SOMENUMBER}
> key, where SOMENUMBER is the convergence criterium in eV per electron. Thus, if your system is a benzene dimer and you want 1 meV 
> convergence on the binding energy you need to set SOMENUMBER to 10e-5. 


Sorry, typo, should be 1e-5

/Elsebeth


> That will likely result in a few extra electronic iterations, compared to the default.
> 
> Best regards
> Elsebeth