[QE-users] Getting wavefunctions from QE

[Hongyi Zhao]

On Thu, Sep 17, 2020 at 3:36 PM Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
>
> Some time ago I wrote the attached piece of code that produces a simple readable output.

I excerpted some notes from
http://electron6.phys.utk.edu/phys250/modules/module%202/interpretation.htm,
as shown below:


The wave function has no direct physical meaning.  It is just one way
of storing information.  It stores all the information available to
the observer about the system.  To make predictions about the outcome
of all measurements, at any time, one has to "do" something to the
wave function to extract information.  One has to perform some
mathematical operation on it, such a squaring it, multiplying it by a
constant, differentiating it, etc.  One has to operate on the wave
function with some operator.  (The operator is a specific instruction
or set of instructions.)  Every observable is associated with its own
operator.


So I still can't figure it out what's the point of extracting
wavefunctions directly.

Regards,
HY

> Add it somewhere (for instance, at the end of PW/src/punch.f90) and add a line
>    CALL simple_output ()
> in some suitable place, such as e.g. after the line
>    CALL punch ('all')
> in PW/src/run_pwscf.f90. Don't even think to use it for anything more complex than simple crystals.You may also add a second line
>    CALL simple_test ()
> that reads what has been written, fills the hamiltonian matrix, diagonalizes it, and goes out of memory for anything more complex than simple crystals.
> It was working last time I used it, no warranty that it will work for you.
>
> Paolo
>
> On Thu, Sep 17, 2020 at 8:32 AM Andrew Xu <andrewaccount at gmail.com> wrote:
>>
>> Dear users,
>>
>> I'm trying to extract the wavefunctions in QE after running pw.x, preferably in non-binary format. In versions less than 6, these two links give me what I want (https://pw-forum.pwscf.narkive.com/UnDfSmzu/how-to-use-the-wave-functions, https://lists.quantum-espresso.org/pipermail/users/2011-June/020897.html); how can I do a similar thing for QE version 6?
>>
>> In particular (I'm using QE 6.3), I noticed the QExml_example in ~espresso/PP/ is missing in QE version 6, and when I do make qexml.x in ~espresso/PP/, I get errors. There's a qexml.f90 in Modules, but doing make qexml.f90, make qexml.o, make qexml_module.mod don't do anything.
>>
>> Best,
>> Andy
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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
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
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> https://lists.quantum-espresso.org/mailman/listinfo/users



-- 
Hongyi Zhao <hongyi.zhao at gmail.com>