CCochard

https://social.sciences.re/@CCochard

MCF à Rennes, ferroélectrique, cristallographie, égalité, neuroD

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Last Notes

2026-08-01 20:56:21 CEST

Je vous ai montré le jardin partagé ?
Il est trop beau 🥰
https://social.sciences.re/system/media_attachments/files/117/021/772/888/611/852/original/42ee72bf62fd3dc5.jpg

2026-03-22 18:16:45 CET

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I think what's noticeable is that there are "women in science" events, but no "men in nursing/education" events

2025-11-11 17:19:39 CET

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did you publish this as blog post? I wanted to share it
(edit: I had checked and couldn't find it so wondered if it's somewhere I didn't look or didn't look properly)

2025-10-04 16:14:10 CEST

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thank you for pointing it out, I was getting annoyed

2025-10-04 15:52:26 CEST

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I think you should! You would find it fascinating (and frustrating at times with the different model used that are never applicable 😅)
My initial assumption seeing the shape you showed was to link it with the electronic density you would have for a benzen ring
(I took the image from here https://chemistry.stackexchange.com/questions/298/pauli-exclusion-principle-and-resonance)
https://social.sciences.re/system/media_attachments/files/115/316/219/535/948/197/original/b0710a834ddb8585.png

2025-10-04 11:53:36 CEST

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also I translated, electrostatic interaction in ionic or coordination or van der Waals bond

2025-10-04 11:52:47 CEST

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I am aware what wavefunctions are...
I wondered why your carbon atoms look so weird in shape.
When I teach atomic radius, I remind students that they are plenty of ways to define radius. 90% probability of electron presence (which I assumed was the model chosen here), metallic/covalent/ionic, van der Waals exclusion radius, etc.

2025-10-04 11:36:57 CEST

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is the black the carbon wave function? (or probability density)

2025-09-30 22:34:40 CEST

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my intuition is that the liaison aren't covalent as you learnt it and as the line would let you infer but coordinate covalent (if my translation is correct). This means that the 2 electrons involved in the liaison come from the lone pair.
My assumption is that the carbon lone pair will be stronger than the one from the nitrogen as there is a formal - charge on the carbon.
This is important because the crystal field will depend on the strength of the ligand, which will be related to the "quality of the bond".
Because Fe2+ has one more electron, I would have assumed that it is more favourable to have a large cristal field splitting, high spin configuration. I suspect the entire thing is more complicated as Fe3+ is not just surrounded by 6N and therefore there will be even more cristal field splitting.
I don't have a clear explanation on the specificity of Prussian blue so a lot of it is hand-wavy assumptions from basic cristal field theory that may not even be (directly) applicable here

2025-09-30 12:04:25 CEST

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I am not sure I understand the question as I assume you know much better than I do about those things.
Iron in both cases is surrounded by 6 ligands (not the 4 you mention earlier, but it's a detail).
You would have crystal field splitting with lifting of the degeneracy between the t2g and eg. with the different electronic (Fe2+:3d6 and Fe3+: 3d5) configuratiion and cristal fields, you will be "filling" your robitals differently in Fe2+ the 6 electrons occupy the low energy t3g (S=0), while in Fe3+, each orbital (3t2g+2eg) has one electron (S=5/2). Each of those crystal field may be in the visible range (but not necessarily)
I assume that when you are trying to excite an electron from Fe2+, t2g, it will go into its own eg and then quickly decays into an eg from the Fe3+ (which should have a smaller local energy) and then Fe3+ t2g and finally back to Fe2+ t2g. One of those transitions (or the combinaison of all of them) will have the characteristic color

2025-09-22 20:55:26 CEST

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maybe a naive question. Are you saying that in this new world matter is no longer made of particles but rather a continuous fabric?

2025-08-04 14:27:17 CEST

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that's crazy. How do the professors justify their positions then? Admin and the brand of their names?

2025-08-04 14:23:52 CEST

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is that a thing?

2025-08-04 14:09:37 CEST

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I can't even comprehend how you could have 6 new research ideas in a year. I suppose it's this professors who have a group of 50 people effectively run by 8 post-docs and 3 lab techs.

2025-08-04 14:03:44 CEST

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I am actually surprised that people would be able to submit 6 anyway. In France and UK, you would kind of submit *up to* 1 big grant/year (and maybe named partner on another one, but that would be a very big year for grants). 6 seems absolutely crazy !

2025-08-04 13:48:38 CEST

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6 submissions/year/person?

2025-06-07 09:50:16 CEST

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I would like to see the funky yarn.
Also, if you have a project, why not?

2025-05-13 07:42:59 CEST

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Really cool!
Made me read about dislocations again.
(The Stone-Wales defect felt to me as a pair of dislocations in a weird geometry. I suspect that's not true, or you need to add a reconstruction element)

2025-04-08 19:58:02 CEST

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if you want to plot it yes. So the shaped I showed you are for an atom with one electron in vacuum, but the actual wave function are extremely difficult to calculate.
Nowadays, with the right equipment and if the sample is right you can measure some of the electron density locally

2025-04-08 19:39:55 CEST

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a big part of my teaching is that I struggle to see wave functions but I accept the interpretation that the square of the wave function is the density of probability and I see a fast particle that moves in the space with more probability in some specific areas

2025-04-08 19:12:36 CEST

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for one electron orbiting an atom, they are reasonably well computed.
You can see the shape of the angular component here .https://chem.libretexts.org/Courses/UWMilwaukee/CHE_125%3A_GOB_Introductory_Chemistry/04%3A_Atoms_Elements_and_the_Periodic_Table/4.08%3A_Orbital_Shape You need to multiply this by the radial one which is *roughly* one bump

2025-04-08 19:09:56 CEST

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is this a physics question or a math question? (or are you just trying to make people cry?)