# Re: [Wien] a doubt from threads in case.InM

It is NOT a divisor ! (does not make sense here). Depending on the method the 4th value is not used or is eg. a friction term for damped newton dynamics.
```
On 08/04/2017 02:26 AM, Gavin Abo wrote:
```
```Currently too lazy to check, are the data values x y z div (where div is
the divisor)?```
```
So (x y z)/div:

0.0. 0.0 0.0 0.0 => (0, 0, 0)/0 = undefined [1] <- If it is not giving a
divide by zero error [2], it sounds like the code is able to handle it
and may be setting any of these divisions to 0.

0.0. 0.0 0.0 1.0 => (0, 0, 0)/1 = (0, 0, 0) <- This may be safer to use.

[1] https://en.wikipedia.org/wiki/Division_by_zero

[2]
https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/392791

On 8/3/2017 9:26 AM, fatima DFT wrote:
```
```Thank you very much Sir.
I feel relax now.
I did a heavy calculation using 0.0. 0.0 0.0 0.0 instead of 0.0. 0.0
0.0 1.0

So I was worried to repeat the calculation by fixing the position with
0.0. 0.0 0.0 1.0.

On Thu, Aug 3, 2017 at 8:31 PM, Laurence Marks
<l-ma...@northwestern.edu <mailto:l-ma...@northwestern.edu>> wrote:

Inlined

On Thu, Aug 3, 2017 at 9:49 AM, fatima DFT <fatimad...@gmail.com

Dear Prof. Peter, Oleg and Marks,

I have two queries for case.inM

First:

I stuck on case.inM file where I want to fix the positions of
the heavier atom for which I do not want to relax the structure.

A comment: fixing atoms does not do what people think, in general
it does not make the convergence of QM methods faster (it can for
CG). The convergence depends upon the number and density of the
elastic eigenvectors  (PORT) and the elastic-electronic system
(MSR1a).

<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_msg03285.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=lMntW40NGNoDrUMHYVU-vXvlVw2pGHikT4XpBt9gMhU&s=-6101yYtzjIzQWcsyC0Zc5AQTUAs08Rf0kz5Ifefu7I&e=>
mentioned keeping 0 0 0 0 in the respective row of atom that I
want to constrain. But this four zeros means the entire line
should be zero

0.0 0.0 0.0 0.0   #Atom    1 Generated by pairhess   >>> Say
it is for La atom.

As per Prof Marks

<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_msg12403.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=lMntW40NGNoDrUMHYVU-vXvlVw2pGHikT4XpBt9gMhU&s=0fcEvAFHmpT7ZahxBQYrqD0Xr0DEsgKPFE0Nk-fLeLM&e=>and
Prof. Oleg

<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_msg01858.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=lMntW40NGNoDrUMHYVU-vXvlVw2pGHikT4XpBt9gMhU&s=GJxC2Mi9-Fts6rULojSPz0X_acMQL2Oe5Ie7WXILcr0&e=>

The only first three number should be zero

0.0 0.0 0.0 1.0   #Atom    1 Generated by pairhess

Could you please clear my doubt that:

How the results will differ if I will use "0.0 0.0 0.0 0.0
#Atom    1 Generated by pairhess" instead of 0.0 0.0 0.0 1.0 ?

I am 99% confident that they are equivalent.

Second:

If I use "x pairhess" to generate the case.inM then does it
copy the case.inM according to the structure files? I just
tested it for two different structures and I saw two different
kind of case.inM.

Yes, different structures with different symmetries have different
symmetry constrained sites so different case.inM.

regards
Fatima

--
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think
what nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu
<http://www.numis.northwestern.edu> ; Corrosion in 4D:
MURI4D.numis.northwestern.edu <http://MURI4D.numis.northwestern.edu>
Partner of the CFW 100% program for gender
equity, www.cfw.org/100-percent <http://www.cfw.org/100-percent>
Co-Editor, Acta Cryst A

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```

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