resp calculation for find charge of MD input

[shabnam borji]

dear cp2k users,

Can you please explain me what is &CHARGE section in MD input?

I'm running resp calculation to find the charge of atoms in my unit cell by use of &CONSTRAINT keyword

&CONSTRAINT .TRUE.

EQUAL_CHARGES

ATOM_LIST ..

&END

but run killed with this error

!-----------------------------------------------------------------------------!

*******************************************************************************

* ___ *

* / \ *

* [ABORT] *

* \___/     CPASSERT failed *

* | *

* O/| *

* /| | *

* / \ qs_resp.F:743 *

*******************************************************************************

===== Routine Calling Stack =====

7 build_atom_list

6 init_resp

5 resp_fit

4 qs_scf_post_charges

3 scf_post_calculation_gpw

2 qs_energies

1 CP2K

Best regards

[Josip Lovrić]

I guess you mean on  EQUAL_CHARGES keyword.

It is used when you know that some of the atoms in your molecule have same charge simple looking at symmetry or something else.

For example hydrogens in a methyl group. This keyword sets high penalty in the calculation of charges if listed charges violate the keyword.

For the error you need to provide more input.

Best,

Josip

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[shabnam borji]

Dear Josip,

thank so much for your reply

I used this keyword to calculate the same charge for all the same atoms without considering symmetry in molecule, just for use in MD input.

So, based on your opinion, this definition of EQUAL_CHARGES is mistake.

I attached my input

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[Josip Lovrić]

It seems you interpreted it incorrectly. I recommend you to read little bit more about force fields and electrostatic potential induced by molecule.

Greetings!

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[Dorothea Golze]

Hi,

for the resp fitting in CP2K, there is a quite comprehensive tutorial:

https://www.cp2k.org/howto:resp

Regards,

Dorothea

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[shabnam borji]

I think, I don't understand something about the charge in CP2k inputs.
I know that partial charge in MD simulation is very important and the most common way to obtain reliable partial charges consists of performing an ab initio calculation and then deriving them from the quantum mechanical potential.
but in all of CP2K examples used one section for charges of similar type of atoms.
I could not distinguish that this is because of the simplicity of the example systems or is a specific definition of charge?

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[shabnam borji]

Dear Dorothea 

thanks for your reply and suggestion