Multiwfn forum

Dear Dr. Tian Lu,
I am trying to study non-covalent interactions between O and S atoms within a single molecule. However, I am encountering an issue with integrating the electron density, as I cannot find the NOCV pair associated solely with this interaction. Consequently, the density of the entire NOCV pair is integrated, leading to an overestimation of the number of participating electrons. The image suggests that there is no electron density between the O and S atoms, yet the CDF curve indicates otherwise. If there is a way to integrate the electron density along the Z direction for selected atoms only, without considering the rest of the electron density of the molecule.
I would be deeply grateful to you for any comments.
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Best regards,
Eugene

Dear Prof Lu,

In my research, I often use IGMH to analyze and visualize non-covalent interactions, both isosurface and 2D plot delta-g_inter vs. sign(lambda2)rho. However, not long ago I encountered a problem in building a 2D plot. In my opinion, the 2D IGMH plot looks wrong, whereas the IGMH blue isosurface looks great.  I tested different versions of Multiwfn, however, I got the same result.  I have previously used IGMH to analyze a similar interaction.  No such problems were observed.  Unfortunately, I can't understand why the 2D IGMH plot looks like this for a given interaction.
I would be very grateful to you for any comments.

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Best regards,
Eugene

Dear Professor Tian Lu,
In my study, there is a need to analyze changes in charge transfer. I would like to use the  Charge Displacement function (CD), which allows you to analyze and visualize changes in charge transfer. However, I cannot figure out how to plot the CD.
As indicated in the article, it is necessary to construct an electron density difference map and integrate it along the z-axis.
"To make the picture of the bonding which emerges from the density difference plots more quantitative, we show, below each one, the curve representing the partial integral of the density difference along the internuclear axis. This thus measures the actual electronic charge fluctuation with respect to the isolated fragments, as one moves from left to right along the internuclear axis (z) and is defined as follows:

where Δq, is the electron density of the complex minus that of the two isolated fragments.  The red dots on the curves in Figures mark the nuclear positions, while the dashed vertical line marks the fragment boundary defined earlier. DOI:10.1021/ja0772647, 10.3390/molecules25020300"

Tell me, please, how do I integrate the electronic density difference map with Multiwfn?
I managed to construct a 1D map of the electronic density difference as specified in detail in the manual to Multiwfn. But I can't figure out how to integrate?

I really hope that such a useful function will appear in the future in the Multiwfn program.

Thank you in advance for your answers.
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Best regards
Eugene

Dear Professor Tian Lu,

In my study, I need to calculate the energy of the halogen bond Cl-O. (Figure1). To do this, I used the SAPT method. According to calculations, the energy of interaction between fragments is estimated at -4.4 kcal/mol. The results of energy decomposition show that long-range interactions (electrostatic and dispersion attraction interactions) prevail. In order to calculate the halogen bond energy, a model calculation was made where halogen atoms were replaced by hydrogen atoms, thus the distances between oxygen and hydrogen atoms are greater than the Van der Waals radius.(Figure3) Thus, the energy between the model fragments was -2.5 kcal/mol. Is it true that the energy of the halogen bond is the difference between the energy of the fragments with the halogen bond and the model system?
(-4.4 + 2.5) / 2 = -0.95 kcal/mol the energy of the halogen bond Cl-O.
Can it be said that the dimer is mainly retained by halogen bonds Cl-O and long-range interactions?

Thank you in advance for your answers.
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Best regards
Eugene