[CP2K:10589] Setting Electronic Temperature in Fermi-Dirac smearing

Kendric Roberts robertsk... at gmail.com
Thu Aug 2 00:03:17 CEST 2018


Okay, thank you very much for the help, I really appreciate. 

On Tuesday, July 31, 2018 at 8:37:59 PM UTC-7, Lucas Lodeiro wrote:
>
> Hi Kendric, the smearing is a contraption to can converge a SCF 
> calculation when the HOMO and LUMO are very near in energy (or the band gap 
> is zero), that is the case for metals or semimetals (because in the SCF 
> procedure you can get some metalic states in the middle of SCF or in some 
> step of your DM). The smearing contribute with entropic-termic energy, and 
> that is a problem, it can fix the SCF but gives some problem in energy, for 
> that is ideal to use a little value for it, but it cannot be too little 
> neither, because a too little value is laki that does not use the smearing. 
> the best way to get the better temperature is search (scan) from what value 
> the energy is converged (by some criteria ej 10E-4 Ha/atom), and then you 
> can know too what is the minimum value to does not have problems in the SCF 
> calculation, you can use one or some configurations. I use in metalics and 
> semimetalics surfaces a value among 0.01 to 0.001 Ha (it is the kb*T energy 
> of smearing, it is around 1000 to 100 K)
>
> i hope i help you
>
> regards
>
>
> 2018-07-31 13:14 GMT-04:00 Kendric Roberts <rober... at gmail.com>:
>
>> Hi I am new to cp2k and am wondering when using smearing for 
>> cell/geometry optimization how should one choose a temperature, which gives 
>> very good scf convergence, but will give inaccurate results? Thanks for the 
>> help. 
>>
>> -Kendric Roberts
>>
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