Re: [Pw_forum] Converged SCF total energies different in 6.0/6.1/6.2

[WF]

Thanks very much for this important information.

Best regards,
Feng

>See this note in file Doc/release-notes:
>
>  * Some constants in the definition of PBE functionals were truncated to
>6 significant digits. While not a bug, this could lead to tiny
differences
>with respect to previous results and other XC implementations (r13592)
>
>More explicitly: some constants that previously were truncated to 6 digits,
are now defined with full precision. This removes minor numerical
discrepancies with the results obtained using libxc.
>
>Paolo

>On Thu, Dec 21, 2017 at 3:11 AM, WF  wrote:

>> Dear all,
>>
>> In tests a normal DFT calculations with Si, I noticed that QE 6.0 and 
>> 6.1 gives exactly same total energy with 6.0 and 6.1 (-15.75190880 
>> Ry), but with QE 6.2.1, the total energy is -15.75191309Ry. I tested 
>> this on two different machines with different compilers, the results 
>> are the same across all of them (at least to last digit). I did some 
>> tests on larger systems also and found even larger difference. This 
>> 1e-5 Ry order of difference is not negligible. Is there anything 
>> introduced in 6.2 leads to this difference? Thanks very much.
>>
>>
>>
>> Best regards,
>>
>> Feng
>>
>>
>>
>>
>> ___
>> Pw_forum mailing list
>> Pw_forum@pwscf.org
>> http://pwscf.org/mailman/listinfo/pw_forum
>>
>
>
>
>--
>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ.
Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax
+39-0432-558222
> -- next part --
> An HTML attachment was scrubbed...
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--
Dr. Feng Wu
Postdoctoral researcher
Department of Chemistry and Biochemistry
University of California, Santa Cruz
Phone: 831-459-2874



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Re: [Pw_forum] Converged SCF total energies different in 6.0/6.1/6.2

[Lorenzo Paulatto]

 From Doc/release-notes

Fixed in 6.2 version

...
* Some constants in the definition of PBE functionals were truncated to
   6 significant digits. While not a bug, this could lead to tiny
   differences with respect to previous results and other XC
   implementations (r13592)


kind regards



On 21/12/17 03:11, WF wrote:
> Dear all,
> 
> In tests a normal DFT calculations with Si, I noticed that QE 6.0 and 
> 6.1 gives exactly same total energy with 6.0 and 6.1 (-15.75190880 Ry), 
> but with QE 6.2.1, the total energy is -15.75191309Ry. I tested this on 
> two different machines with different compilers, the results are the 
> same across all of them (at least to last digit). I did some tests on 
> larger systems also and found even larger difference. This 1e-5 Ry order 
> of difference is not negligible. Is there anything introduced in 6.2 
> leads to this difference? Thanks very much.
> 
> Best regards,
> 
> Feng
> 
> The input file is attached:
> 
> 
> 
> 
> 
>      calculation='scf'
> 
>      outdir='./tmp'
> 
>      prefix='si'
> 
>      wf_collect = .true.,
> 
> /
> 
> 
> 
>      ibrav=2,
> 
>      celldm(1) = 10.263,
> 
>      nat=2,
> 
>      ntyp= 1,
> 
>      ecutwfc = 40,
> 
> /
> 
> 
> 
>      mixing_mode='plain'
> 
>      mixing_beta = 0.7,
> 
>      conv_thr =  1.0d-10,
> 
> /
> 
> ATOMIC_SPECIES
> 
> Si  1.0 Si_ONCV_PBE-1.1.upf
> 
> ATOMIC_POSITIONS {alat}
> 
> Si 0.00 0.00 0.00
> 
> Si 0.25 0.25 0.25
> 
> K_POINTS (automatic)
> 
> 4 4 4 0 0 0
> 
> ==
> 
> --
> 
> Dr. Feng Wu
> 
> Postdoctoral researcher
> 
> Department of Chemistry and Biochemistry
> 
> University of California, Santa Cruz
> 
> Phone: 831-459-2874
> 
> 
> 
> ___
> Pw_forum mailing list
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> http://pwscf.org/mailman/listinfo/pw_forum
> 

-- 
Lorenzo Paulatto - Paris
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Re: [Pw_forum] Converged SCF total energies different in 6.0/6.1/6.2

[Paolo Giannozzi]

See this note in file Doc/release-notes:

  * Some constants in the definition of PBE functionals were truncated to
6 significant digits. While not a bug, this could lead to tiny
differences
with respect to previous results and other XC implementations (r13592)

More explicitly: some constants that previously were truncated to 6 digits,
are now defined with full precision. This removes minor numerical
discrepancies with the results obtained using libxc.

Paolo

On Thu, Dec 21, 2017 at 3:11 AM, WF  wrote:

> Dear all,
>
> In tests a normal DFT calculations with Si, I noticed that QE 6.0 and 6.1
> gives exactly same total energy with 6.0 and 6.1 (-15.75190880 Ry), but
> with QE 6.2.1, the total energy is -15.75191309Ry. I tested this on two
> different machines with different compilers, the results are the same
> across all of them (at least to last digit). I did some tests on larger
> systems also and found even larger difference. This 1e-5 Ry order of
> difference is not negligible. Is there anything introduced in 6.2 leads to
> this difference? Thanks very much.
>
>
>
> Best regards,
>
> Feng
>
>
>
> The input file is attached:
>
> 
>
> 
>
> calculation='scf'
>
> outdir='./tmp'
>
> prefix='si'
>
> wf_collect = .true.,
>
> /
>
> 
>
> ibrav=2,
>
> celldm(1) = 10.263,
>
> nat=2,
>
> ntyp= 1,
>
> ecutwfc = 40,
>
> /
>
> 
>
> mixing_mode='plain'
>
> mixing_beta = 0.7,
>
> conv_thr =  1.0d-10,
>
> /
>
> ATOMIC_SPECIES
>
> Si  1.0 Si_ONCV_PBE-1.1.upf
>
> ATOMIC_POSITIONS {alat}
>
> Si 0.00 0.00 0.00
>
> Si 0.25 0.25 0.25
>
> K_POINTS (automatic)
>
> 4 4 4 0 0 0
>
> ==
>
>
>
>
>
> --
>
> Dr. Feng Wu
>
> Postdoctoral researcher
>
> Department of Chemistry and Biochemistry
>
> University of California, Santa Cruz
>
> Phone: 831-459-2874 <(831)%20459-2874>
>
>
>
>
>
> ___
> Pw_forum mailing list
> Pw_forum@pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>



-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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[Pw_forum] Converged SCF total energies different in 6.0/6.1/6.2

[WF]

Dear all,

In tests a normal DFT calculations with Si, I noticed that QE 6.0 and 6.1
gives exactly same total energy with 6.0 and 6.1 (-15.75190880 Ry), but with
QE 6.2.1, the total energy is -15.75191309Ry. I tested this on two different
machines with different compilers, the results are the same across all of
them (at least to last digit). I did some tests on larger systems also and
found even larger difference. This 1e-5 Ry order of difference is not
negligible. Is there anything introduced in 6.2 leads to this difference?
Thanks very much.

 

Best regards,

Feng

 

The input file is attached:





calculation='scf'

outdir='./tmp'

prefix='si'

wf_collect = .true.,

/



ibrav=2,

celldm(1) = 10.263,

nat=2,

ntyp= 1,

ecutwfc = 40,

/



mixing_mode='plain'

mixing_beta = 0.7,

conv_thr =  1.0d-10,

/

ATOMIC_SPECIES

Si  1.0 Si_ONCV_PBE-1.1.upf

ATOMIC_POSITIONS {alat}

Si 0.00 0.00 0.00

Si 0.25 0.25 0.25

K_POINTS (automatic)

4 4 4 0 0 0

==

 

 

--

Dr. Feng Wu

Postdoctoral researcher

Department of Chemistry and Biochemistry

University of California, Santa Cruz

Phone: 831-459-2874

 

 

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