[Pw_forum] Error in routine bfgs (1): dE0s is positive which should never happen

[Alaska Subedi]

Dear Paolo,

I tried to reproduce this problem at different nodes in the cluster,
and the problem seems to be node dependent. Let me verify that it is
not the problem of the environment before I take more of your time.

Best,
Alaska



On Fri, Sep 23, 2016 at 1:58 PM, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
> Please send me an output showing the problem you mention. Paolo
>
> On Fri, Sep 23, 2016 at 11:31 AM, Alaska Subedi <asubedi at gmail.com> wrote:
>>
>> On Thu, Sep 22, 2016 at 6:03 PM, Paolo Giannozzi <p.giannozzi at gmail.com>
>> wrote:
>> > Once the error is detected, the code stops immediately and prints
>> > nothing
>> > useful. Where do you see that there are no cell parameters? And when:
>> > during
>> > a variable-cell calculation, or also (or only) in a fixed-cell one? If I
>> > remember correctly, cell parameters are reprinted on putput at each step
>> > in
>> > the former case, never in the latter.
>>
>> In a vc-relax calculation, the code prints atomic_positions but not
>> cell_parameters after this error. Generally, vc-relax prints both
>> cell_parameters and atomic_positions. But this does not happen when
>> the code stops with this error. It would be nice if it also printed
>> cell_parameters before exiting.
>>
>> Thanks,
>> Alaska
>>
>>
>> >
>> > Unfortunately the code performing the various MD and structural
>> > optimizations is rather obscure and it is not straightforward to figure
>> > out
>> > how to modify it.
>> >
>> > Paolo
>> >
>> > On Thu, Sep 22, 2016 at 2:56 PM, Alaska Subedi <asubedi at gmail.com>
>> > wrote:
>> >>
>> >> Dear Paolo,
>> >>
>> >> Sorry to resurrect this after a long time.
>> >>
>> >> This problem is innocuous but annoying nonetheless. I am using QE to
>> >> relax structures generated by USPEX. For around five percent of the
>> >> structures, I get this error. When this error happens, pw.x exits by
>> >> only printing atomic positions but not the cell parameters. This gives
>> >> problems to USPEX.
>> >>
>> >> I tried to find which call to output_tau is responsible for this, to
>> >> no avail. I'd greatly appreciate if someone can point me to a
>> >> modification that will make the code output both the cell_parameters
>> >> and atomic_positions during exit after this error.
>> >>
>> >> Thanks,
>> >> Alaska
>> >>
>> >>
>> >>
>> >> On Mon, Sep 22, 2014 at 9:52 PM, Paolo Giannozzi
>> >> <paolo.giannozzi at uniud.it> wrote:
>> >> > This kind of errors invariably happens when you are very close
>> >> > to the minimum and you have some numerical noise on forces. It
>> >> > is useless in my opinion to insist: your system is sufficiently
>> >> > relaxed
>> >> >
>> >> > Paolo
>> >> >
>> >> > On Mon, 2014-09-22 at 13:29 +0530, amitharani wrote:
>> >> >> Hi
>> >> >> I am getting an error { Error in routine bfgs (1): dE0s is positive
>> >> >> which should never happen }. The output file is attached for your
>> >> >> kind
>> >> >> perusal.This is the 2nd time I am getting the same error
>> >> >> consecutively.
>> >> >> I followed what Nick had suggested on the pwforum to take the
>> >> >> relaxed
>> >> >> co-ordinates, make a new input file and resubmit, but it didn't
>> >> >> work.Thanks.
>> >> >>
>> >> >>
>> >> >> _______________________________________________
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>> >> >
>> >> > --
>> >> > Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
>> >> > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>> >> > Phone +39-0432-558216, fax +39-0432-558222
>> >> >
>> >> > _______________________________________________
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>> >
>> >
>> >
>> >
>> > --
>> > 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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>> > http://pwscf.org/mailman/listinfo/pw_forum
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>
>
>
>
> --
> 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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