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

[Dev Rana]

Thank you Lucas, for that simple explanation. I'll try this out.

On Wednesday, December 16, 2020 at 10:38:12 AM UTC-5 Lucas Lodeiro wrote:

> 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 (<d... 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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>
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