Recent Posts

1

General Questions and Answers / Re: Regarding one existed .py file from software tutorial itself. Opening at builder

« Last post by Anders Blom on Yesterday at 19:14 »

Not to be impolite but I honestly do not understand what you are asking, you need to be be clearer.

If you are following the tutorial and something doesn't work or you have a question on a particular step, you can ask about that. But don't expect other people to do your work for you...

2

General Questions and Answers / Orbital coefficients

« Last post by lohy on Yesterday at 13:14 »

Hi,

Is it possible somehow to get the orbital coefficients out when calculating the eigenstates of a molecule?

I cannot find anywhere in the documentation that mentions this, so it might be that you call it something else.

thank you in advance,

Louise

3

General Questions and Answers / Re: Unit trouble dipole moments

« Last post by MariaWJ on Yesterday at 09:52 »

Thank you for the response, but should polarization then not be a good property to calculate for a monolayer? Or is that best for a bulk material? I have tried running it but again I get mysteriously large values, in fact almost the same as when I do the dipole over the volume. That makes me question, is the polarization actually calculated through the dipole as in the scripts?

4

General Questions and Answers / Re: Regarding one existed .py file from software tutorial itself. Opening at builder

« Last post by techenthusiast on Yesterday at 08:30 »

Dear Admin, Any update on this? Kindly, if feasible . Thank You.

5

General Questions and Answers / Re: Implementing a new Reactive Forcefield

« Last post by AsifShah on Yesterday at 04:03 »

Dear Admin,
Any update on this?
Here is the actual paper where this ReaxFF was implemented


https://pubs.acs.org/doi/10.1021/acs.jpcc.2c01075#:~:text=Abstract-,We%20present%20a%20new%20Reactive%20Force%20Field%20(ReaxFF)%20parameter%20set,simulations%20of%20Mo%2DS%20structures.&text=2-,structure%20in%20crystallization%20simulations.,unknown%20rock%20salt%20MoS%20structure.

6

General Questions and Answers / Re: Unit trouble dipole moments

« Last post by Anders Blom on May 1, 2024, 20:10 »

I think the way we evaluate the dipole from the electron density is basically limited to molecules. For monolayers with voltages applied etc, it's more relevant to consider the dielectric response, i.e. the field gradient in the material vs. the external electric field.

7

General Questions and Answers / Re: Unit trouble dipole moments

« Last post by MariaWJ on May 1, 2024, 09:39 »

So the final unit should then be bohr*e, great. I am actually using electron difference density with a script adapted from your tutorial, but thanks for the heads up. I have a final curious question, would this dipole approach actually be applicable for periodic boundary conditions or is this purely molecular?
I am trying to calculate both polarization using the dipole for a monolayer with a bias. The bias I create with the metal plates but the dipole and  seem to respond rather drastically yielding too high values, so I just wondered if maybe I shouldn't do dipole with periodic boundaries?

Hope you have some insight

8

General Questions and Answers / Re: Unit trouble dipole moments

« Last post by Anders Blom on April 30, 2024, 20:28 »

Yes, it's a mistake. At some point in the ancient past numpy.dot would strip off the unit so we had to reapply now, but now it gets multiplied in with the unit already applied.

Just skip the length_unit**3 and it works better! However, also see https://forum.quantumatk.com/index.php?topic=10790 about why you should use the ElectronDifferenceDensity, rather.

9

General Questions and Answers / Re: Phonon dispersion is senstitive to "processes_per_displacement" paramter of DM?

« Last post by Anders Blom on April 30, 2024, 20:19 »

Aha, interesting... I'll make sure to forward this to our developers, however at least now you have a workable way to run the calculations fast, and correctly!

10

General Questions and Answers / Unit trouble dipole moments

« Last post by MariaWJ on April 30, 2024, 14:06 »

Using the script for calculating dipole moments seems to have an error in the unit. I follow the tutorial: https://docs.quantumatk.com/manual/Types/ElectronDensity/ElectronDensity.html . What is the correct unit for the dipole moment?

I think the problem is this line:
# Calculate the volume of the volume element.
dV = numpy.dot(dX, numpy.cross(dY,dZ)) * length_unit**3

When I print dV.unit() I get bohr**6, I assume that is a mistake.
So is the final dipole printed in the unit of e*bohr or is it maybe Debye? or am I misunderstanding something?

Please help me, I am very confused!