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#1Quantum Chemistry»RI approximation»2023-11-30 11:14:09

RGUceda
Replies: 1

Good afternoon:
My question is very general, but I have not been able to find a detailed and satisfactory answer: what is the RI approach? I have seen that it is used quite a lot, for example, together with CC2, and that it helps in calculation times, but I have not found either by what order of magnitude it speeds up the calculation or a detailed explanation of why it allows faster calculations.
Thanks in advance

#2Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-06-26 09:38:38

Hello again
I have a new question, regarding the magnetic and electric moments of the transition. When I obtain the module of the magnetic moment with the option that you told me, everything has the same phase, which makes sense due to the definition of the option (4: Norm, sqrt(x^2+y^2+z^2) ). However, when an analogous procedure is followed for the electric momentum, the .cub shows positive and negative densities. Why this difference between one moment and another?

Thanks in advance

#3Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-26 14:02:38

I just re-downloaded the program and now the option did appear. Thank you very much for your help

#4Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-26 06:52:38

Yes, that would be just what I would want. However, option 4 does not appear for me, only options 1-3, referring to the coordinate axes. I'm using MultiWFN 3.8, so I don't understand why the option doesn't appear...

#5Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-24 15:11:18

I complement what I said in the previous comment: if I reorient my molecule and recalculate I can achieve that there is only a magnetic moment in one of the components. However, I am studying lots of molecules (with also many atoms) and that would be very laborious. Bearing in mind that the program provides the X, Y and Z components, couldn't the total be obtained?

#6Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-23 15:12:33

Hello. Thanks for your kind reply.
However, I still have a question: wouldn't it be possible to obtain the total magnetic composition, and not the component per axis? In case it can't, can't I get it somehow? I have tried to do it with cubman without success. Thanks in advance.

#7Multiwfn and wavefunction analysis»Orbitals in a Transition State»2023-05-18 18:01:22

RGUceda
Replies: 1

Good afternoon:
Thank you very much in advance. I have a question regarding the orbitals of a transition state. Since in a transition state we see how a bond is created or destroyed, I understand that orbitals can be very informative. However, I have seen works that talk about HOMO-1, HOMO, LUMO and LUMO+1. What is the physical significance of those empty orbitals or HOMO-1?

Thank you so much

#8Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-09 20:44:46

The problem I'm seeing is that it doesn't matter what geometry I give Gaussian to do the optimization (even to calculate only the CD): the molecule rotates again and has a different geometry. It's something like Gaussian moving the reference system itself and the axes, so it doesn't matter if I change the geometry I give it. Do you know of any other tricks or ways to tell Gaussian not to make that change?

Thanks

#9Re:Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-07 09:35:01

However, I have helical molecules and the cases in which there is only one important component (for example 2.1 0.001 0), which coincides with the axis of the helix, are very illustrative. In others, due to the orientation of the molecule, there are two axes with important contributions (for example 1.8 0.003 1.5). The program asks you which component you want to get from the analysis. I would like to
have only one important component so that the images obtained are comparable (if it only has an X component, I take the projection on the X axis, etc...). A possible alternative would be to obtain the cube of the magnetic moment of the transition, without projection on any axis, but I think that this option does not exist.

Thanks again.

#10Multiwfn and wavefunction analysis»magnetic component of a transition»2023-05-06 19:13:47

RGUceda
Replies: 12

Hello good:
First of all, my sincere congratulations on your very versatile program. It's a fantastic tool.

I am interested in looking at the magnetic component of a transition. I have noticed that sometimes the transition only has a significant value on one of the axes, while sometimes both axes have significant values. Can similar structures be compared where in one case only one axis has contribution with another where two axes have?

Otherwise, and even if it could be compared, how could you make the transition that is expressed as, say 3.4 0 -2.8 become (random numbers) 5 0 0.1? In other words, it becomes significant in only one of the components

I have tried to rotate the geometry and recalculate but so far no success and still getting the same thing. I know my question is not really about Multiwfn, but I think you could help me.

Thanks a lot.

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