[CP2K-user] [CP2K:14403] Re: How do you determine how many ADDED_MOS to use?

[Lucas Lodeiro]

Hi Dev,
As Marcella said, the number of MOs added is system dependent, but for a
typical smearing temperature (1000-2000 K) if you add  20% of total
occupied orbitals, usually works fine. This is the standard in some codes
like Quantum Espresso.

El mié, 16 dic 2020 a las 12:06, Dev Rana (<dev.... at gmail.com>) escribió:

> Hi Marcella,
>
> Thank you for your response. I found this helpful reference which helps
> you determine the correct smearing temperature. It's not a simple
> calculation, but it guides you on how to find the optimal temperature based
> on some regression testing. I'm 100% sure that if they were to also plot
> time for simulation to complete, we would see an optimal smearing
> temperature which speeds up calculations as well. Albeit, with a sacrifice
> in precision. But could be possible.
>
> Anyhow, reference: http://theossrv1.epfl.ch/Main/ElectronicTemperature
>
> Best Regards,
> Devyesh Rana
>
> On Wednesday, December 16, 2020 at 2:17:18 AM UTC-5 Marcella Iannuzzi
> wrote:
>
>> Dear Devyesh Rana
>>
>> The first warning message is telling you that also the lowest states are
>> involved in the smearing.
>> This should be avoided.
>> Probably you have a system with a narrow span in MOS energies and a too
>> large smearing temperature.
>> The number of added MOS depends on the density of states around Fermi.
>> You want to cover a few eV, but how many depends on the smearing
>> temperature you give.
>>
>> Best
>> Marcella
>>
>>
>> On Wednesday, December 16, 2020 at 3:20:40 AM UTC+1 Dev Rana wrote:
>>
>>> How do you determine how many ADDED_MOS to use?
>>>
>>> I'm currently obtaining a warning:
>>>  *** WARNING in qs_mo_occupation.F:492 :: Fermi-Dirac smearing includes
>>> ***
>>>  *** the first MO
>>>  ***
>>>
>>>
>>>  *** WARNING in qs_mo_occupation.F:503 :: Fermi-Dirac smearing includes
>>> ***
>>>  *** the last MO => Add more MOs for proper smearing.
>>>  ***
>>>
>>> However, I don't know how to choose the right number of MOs for proper
>>> smearing.
>>>
>>> Best Regards,
>>> Devyesh Rana
>>>
>> --
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