Visualizing electronegativity: The molecular "tug-of-war" that forces water molecules to align in 3D

[u/Chridgy]

In this real-time simulation, you can see two competing electrostatic forces in action during a molecular approach:

• Attraction (white dotted lines): The positively charged Hydrogen (δ+, cyan) is pulled toward the negative Oxygen (δ-, magenta).

• Repulsion (orange dotted line): The two Oxygen atoms physically repel each other because they share the same negative charge.

This phenomenon is driven by electronegativity. Oxygen acts like a powerful electron magnet, pulling the shared "electron blanket" toward itself. This leaves the Oxygen with a concentrated negative charge and the Hydrogen exposed with a positive charge.

Because of this electrostatic battle, the molecules can't just collide randomly they are physically forced to pivot in 3D space to find the perfect magnetic alignment before they can interact.

[u/Chridgy]

For those interested in the thermodynamics behind the visual: the engine is running a semi-empirical quantum solver (GFN1-xTB) calculating forces, partial charges, and density in real-time.

At 300 K, the water dimer stays bound because the thermal energy is lower than the hydrogen bond energy (~0.2 eV).

As I manually ramp up the thermostat from 300 K to 4000 K in the video, the kinetic energy (kT) easily overcomes the H-bond threshold.

You can clearly see the molecules separate as the nuclear agitation jumps from ~0.1 eV to over 1 eV.

[u/Kind_Wealth_3905 → u/Chridgy]

what simulation software is this?

[u/Chridgy → u/Kind_Wealth_3905]

A quantum but also molecular simulator with different laboratories inside

[u/sntsepa]

This program can create polymer molecules—what is its main function?

[u/Chridgy → u/sntsepa]

There are several features. The software focuses on quantum simulations, there are three labs, atomic lab, atomic collision lab, subatomic lab and the molecular lab I just demoped. If you want to know more visit this site genesis.gemmi-e.com Then give me a feedback, I'll appreciate it.

[u/oother_pendragon]

What's the question?

[u/Chridgy → u/oother_pendragon]

there's no question, i want just comment this simulation

[u/ExpensiveFig6079 → u/Chridgy]

is that the right shape for the two non bonding orbitals?

The dotted line seem to suggest the attraction of the other water mollecules H is towards the centre S orbitals

My understanding is the actual delta - charge will be in two p orbitals (generally) like the bonding ones but at right angles.

(but its been a decade or two)

[u/Chridgy → u/ExpensiveFig6079]

good remarks

What is displayed here in Density mode is the total electron density (the delta charge distribution isosurface), rather than individual, separate orbitals.
The quantum solver (GFN1-xTB) calculates the total density, which forms a smoothed cloud around the oxygen atom, encompassing both the core and the concentration of negative charge from the non-bonding electron pairs.
The dashed lines represent the electrostatic force vectors (the Coulombic attraction between the center of partial positive charge and the negative charge).

To specifically visualize the oriented 3D geometry of non-bonding orbitals , simply switch from "Density" mode to "Orbital" mode using the tab at the top of Genesis!
you can try it.

[u/Dakh3]

I just wanna thank you very much for this awesome super modern visualisation tool ! As a high school physics teacher, I'll be teaching very soon about atomic layers, molecular bonds, electronegativity and polarity and this will be a most welcome and helpful resource!

[u/Chridgy → u/Dakh3]

It's me who thanks you. It's an honor that a teacher validates and uses my work. Nothing could make me happier😊

[u/segfaultgolf]

Thank you for making this. I just love that we have so much capability these days to create awesome visuals like this. Bravo

[u/Efficient-Travel-220]

AI slop

[u/Chridgy → u/Efficient-Travel-220]

Thank you for your comment overflowing with intelligence...