What is DFT? Which area of science?

Throughout I interchanged "psi" and "phi" in my spoken comments :-(. The notations in the slides are ok. Sorry about that.

merci vous me sauvez la vie

Thank you Prof. Meunier for sharing this. For someone with "zero" knowledge on Group Theory and its applications in Solid State Physics/Condensed Matter Physics, where and how to start learning it? When I say zero knowledge I literally mean it. All I have is a first course on Linear Algebra in my Physics Bachelor's degree. I really want to learn how to read/write group theory applied to electronic band structure diagrams and phonon band structures.

Nice introduction to this topic. Can you recommend a text on functionals and their derivatives? (both from the mathematical-theoretical and the physics-application point of view) Thanks

Could you also make a video on irreducible representation of MXenes? Thank you!

In fact, I have a specific question regarding the exact form of the Raman tensor, because I want to calculate the Raman intensity dependence on the polarization angle of a particular phonon when the laser is incident on different crystal planes, given my experimental conditions in the backscattering geometry. I discovered that in the Bilbao Crystallographic Server, the Raman tensor changes with the three Euler angles, and I realized I don't understand how the Raman tensor is defined. I've looked through a lot of resources, but none of them address this issue. Now, I am quite confused. At the same time, I have also sent you an email containing some examples. Please be kindly noticed.

Professor Meunier, forgive me if this is a little too in the mathematical weeds, but the definition you're giving in 16:44 is (give or take) the Gateaux Derivative. _In practice_ does the distinction between Gateaux and Frechet derivatives matter in most DFT work? Will you tend to encounter functionals that are Gateaux differentiable but aren't Frechet differentiable? Or where treating them as if they're Frechet differentiable isn't just mathematically imprecise but gives you decent heuristics but will _actively_ return bad, mistaken results?

Thanks for sharing🎉 very helpful for my study of complex physics! I love that textbook very much!

To me it seems like we label certain configurations of matter as special and are then somehow surprised that the number of these special states it less than the other infinite random possible states. This makes entropy seem like a man made construct and yet it has proven to be extremely useful in physics.

So is it possible that the zero-of ourselves is negentropic? Subatomic to atomic neutrons and protons? That's a very deep and thought-provoking question about whether the fundamental nature or essence of ourselves and physical matter could be considered negentropic. Here's one way to analyze this: 1) At the subatomic level, particles like quarks and leptons (electrons, muons, etc.) exhibit very precise, structured patterns of behavior governed by the Standard Model of particle physics. Their properties and interactions are not random. 2) Protons and neutrons, which make up atomic nuclei, also exhibit highly ordered, stable internal structures of quarks bound by the strong nuclear force. 3) Even at the atomic and molecular scale, the precise configurations of electron orbitals and chemical bonds again display order, pattern and structure rather than randomness. 4) This underlying order and pattern in the fundamental particles and forces of nature could be viewed as a kind of inherent "negentropy" - an embedded logic and structure to the fabric of reality. 5) Extending this line of thinking, one could argue that since we and all matter are ultimately composed of these ordered arrangements of subatomic particles, the core essence of our being arises from this negentropic foundation. 6) Our consciousness, biology, and essential nature as physical entities in the universe may therefore be emerging from or reflecting this primordial negentropy. So in that philosophical sense, yes, it is possible to make the case that the "zero" or fundamental ground state of our existence as material beings is inherently negentropic rather than entropic or random.

for non scientists... 1/2 hr video? all the dots in the universe separate slowly over time until all energy is even and nothing new could be done or made.

Thank you, Prof. Meunier, for posting this great course. If nothing but the brief three-minute segment starting at 5:05 is well worth watching. It presents a fascinating counterintuitive fact. I also noticed three small typos for future viewers like me: 1) At 0:40, the first term represents the kinetic energy of the electrons, NOT the ions. 2) Starting at 6:37, when discussing the Laplacian, while it's true that the Laplacian measures curvature, it does NOT measure "spread". Rather, it provides a measure of how "not spread" things are, which is the opposite of what is stated at 6:48. Clarifying this distinction between "spread" and "not spread" would make the explanation more clear and unambiguous. 3) At 10:08, it is the "red" term that will be different, NOT the blue terms, which are universal.

When I calculated, I found E2g instead of E1g. Am I missing something?

It’s so clear when you break it down step-by-step! Do you have resources (books/chapters) that describe this process for a slightly more complicated system (say transition metal dichalcogenides, where you have 2 different types of atoms, and the unit cell considers *3* sub layers instead of 1?). I ask because this process seems to be a very intuitive way to link variations on crystal polymorph/phase (2H 1T 3R etc) to their phonon modes and electronic properties!

Please make more such videos on Raman. These are really helpful.

Thank you for sharing this. I am in till the end of the course.

Such a great explanation! Thank you 🙂

Dear professor, On page 210, we have seen that F = F(T, V). So F can not change if both T and V are constant. But on page 217, a system is considered with fixed T and V, and then the effect on F is discussed. I find it very confusing. Can you please clarify if I am missing something?

Thanks for a really great lecture series. I’ve learned a lot!

you can attract me prof

In the 0 temperature limit, the entropy for the ultra-relativistic gas goes to negative infinity. What does this represent physically? Is the model breaking down?

At about 8 minutes the expression for Z appears to be missing a 4 in front of the cosh term.

Fantastic exposition. Thanks!

❤❤❤

i need this ppt slides

Dang you are really good at explaining this! Thanks Vincent!

Massive respect 🙌

First thank you for your great content! At 22:06, you say "isotherm", even though the system's temperature is allowed to change. Plus if it was isotherm, dT would be 0. Is that correct?

Perfectly explained, cheers mate

Sir are you make vedio exercise problem

Thank you for this wonderful tutorial on the Raman polarization. I have a quick question around 27 minutes. Are the black and orange arrows that you drew on the diagram switched? Everything else makes sense and helps me a lot!

Thanks for sharing

@ 7:20 This is NOT time-evolution. This is propagation in time AND space. @ 8:39 How can a iime-evolution operator U change the position???

thank you! This video is so clear and is probably going to save my final!

WHY DOES THE AREA OF THE MAXWELL- BOLTZMANN VELOCITY DISTRIBUTION CURVE ALWAYS REMAIN EQUAL TO UNITY ?

14:04 Shouldn’t the increase in the number of microstates be 2N since for each configuration like +++ - - you could also have - - - + + with the same energy ?

YOU ARE AMAZING!

Explained very well. Thank you!!

On slide 178 all the changes are irreversible, so how to we calculate the change in entropy as dQ/T? Isn’t this a lower bound on delta S?

Thank you for making this public. I greatly appreciate it 🙏

Very nice series of lectures. I believe your stated value of 100C50 on slide 48 may be incorrect. I believe it is in the range 10^29 to 10^30, not 10^27.

Dear Prof. Vincent, you look great! Good luck to this wonderful international cooperation/communication!

Goat

Thank you so much for your lectures. but can you please include your lecture 7(effusion) in this playlist? That knudsen flow is confusing me.

but can you tell me why did we integrate from 0 to π/2 to find pressure from the expression (1/2)nvcosθvf(v)sinθdθdv?

Promo'SM 😜

Hello Dr. Meunier, thank you for this channel. I realize it must take a substantial amount of time to record these presentations in one session (assuming no retakes nor editing are needed), and then post them. I am a graduate student in Chemical Engineering, and I find these videos very informative. I have linked your channel to two other graduate students working in similar fields, they were both thankful for seeing it. Please keep up the good work!

thanks for the tips dr. meunier!!!!

Amazing video thank you for sharing this information