[CP2K-user] [CP2K:20181] Different Total energy and ENERGY| Total FORCE_EVAL ( QS ) energy [a.u.]

[Benjamin Shi]

I also attach my input file here as I'm not sure if any of the settings 
I've picked could cause some difference in the re-evaluation of the energy.

On Monday, May 6, 2024 at 5:43:52 PM UTC+10 Benjamin Shi wrote:

> Hi Jurg,
>
> Thank you very much for the information. Just to confirm, the "Total 
> FORCE_EVAL (QS) energy" quantity is the correct energy to use?
>
> For this calculation, I have used an EPS_SCF of 5E-7, which is tighter 
> than default. Are you suggesting that the discrepancy between "Total 
> energy:" and "Total FORCE_EVAL (QS) energy" which I'm observing here means 
> that my forces could be noisy or energy isn't well-converged? Previously, I 
> have confirmed that the force is well-converged by modifying/increasing 
> EPS_DEFAULT and it changes atomic forces by less than 0.01 eV/A.
>
> Best wishes,
> Benjamin
>
> On Monday, May 6, 2024 at 5:34:01 PM UTC+10 Jürg Hutter wrote:
>
>> Hi 
>>
>> this is a problem of consistency of forces and energies. During the SCF 
>> some energy terms (especially with diagonalization) are calculated from 
>> the 
>> input density and some from the output density. Upon convergence 
>> the energy is recalculated in a consistent manner and forces are wrt this 
>> energy. 
>> However, this shouldn't matter as long as the density is sufficiently 
>> converged. 
>> In your case I would suggest to improve SCF convergence, as that will 
>> also 
>> considerably reduce the noise (or error) on your forces (good for ML). 
>>
>> regards 
>> JH 
>>
>> ________________________________________ 
>> From: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of 
>> Benjamin Shi <benjam... at gmail.com> 
>> Sent: Sunday, May 5, 2024 11:56 AM 
>> To: cp2k 
>> Subject: [CP2K:20171] Different Total energy and ENERGY| Total FORCE_EVAL 
>> ( QS ) energy [a.u.] 
>>
>> Dear CP2K developers, 
>>
>> I am writing to enquire as to what the difference is between the energy 
>> given by "Total energy:" and "ENERGY| Total FORCE_EVAL ( QS ) energy 
>> [a.u.]:". As seen in attached output file, I'm finding a slight difference 
>> in the two energy values. Does this arise because I incorporate Fermi 
>> smearing? In the context of training machine learning potentials, which 
>> quantity would be the correct quantity to use that is consistent with the 
>> forces that are printed out? 
>>
>> Thank you for your help, 
>> Benjamin 
>>
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "cp2k" group. 
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to cp2k+uns... at googlegroups.com<mailto:cp2k+uns... at googlegroups.com>. 
>>
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/cp2k/34a1a6d5-ed13-4c3b-b6ed-574aea8d4228n%40googlegroups.com
>> <
>> https://groups.google.com/d/msgid/cp2k/34a1a6d5-ed13-4c3b-b6ed-574aea8d4228n%40googlegroups.com?utm_medium=email&utm_source=footer>. 
>>
>>
>

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/07f7de63-7184-4791-93db-32030b96301en%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20240506/8cb3a160/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: revpbe0.inp
Type: chemical/x-gamess-input
Size: 33594 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20240506/8cb3a160/attachment-0001.inp>