Lecture 21: Periodic Lattices Part 2

MIT 8.04 Quantum Physics I, Spring 2013
Instructor: Allan Adams

In this lecture, Prof. Adams reviews results derived for periodic potential and continues to discuss the energy band structure. The latter part is devoted to the physics of solids.

License: Creative Commons BY-NC-SA

[yumipharoh]

omg i never ever seen a teacher this good before.hes a gift to quantum world

[lakshithalathpandura]

Guys! Please go through Problem Sets and Solutions. Those have decent amount of information that he didn't explain in the class.

[nikhilsen]

So in lecture some one asked a question (or stated one observation) that what will happen if we apply an AC current to a perfect crystal of copper.So what is that entire story.

[jordanedmunds]

Perhaps I missed this, but why do common eigenfunctions of the energy and the translate by L operator necessarily form a complete basis?

[FullTimeHypocrite]

still dont get how i can visualize negative effective mass for the electron in a periodic lattice
the water stands for what ? the atom cores ? but its not like these cores can move plus the effective mass depends on momentum of the electron
thats as if the table tennis ball would move toward earth after hitting a certain speed, i think this acutally happens tho as he shows in some of the later lectures BUT how does it translate to the electron? somehow the electron is dragged backwards from the atom cores but its not like the electron drags them along with it. Can i somehow picture this with electron phonon interactions?

[eitanas]

hello MIT!
thank you for these great lectures.
i was wondering if one can find the exams solutions if there are any.
it would be a great help!
thank you

[ranjeetsingh-fwij]

So at q=0 energy is zero. As we increase q velocity first increases reaches its Maxima and then starts decreasing . At q= π/l velocity becomes zero while the energy is maximum in its band. On further increasing energy we get to second band so the variation of energy with q graph changes. So how is that electron making Bloch oscillations.

[andrewandrus]

What is this about "when you see lions, think lions"

[CHistrue]

My knowledge has climbed periodic lattices while watching this series but I am afraid that at shell number 21 my brain's magnetic moment just can't quite align.

[mfoucault]

nice explanation on the Dirac's positrons so to speak sayin

[blabla-kpor]

has anybody ever seen this guy actually drink? i always just see him holding his drink

[vasugoel]

How come this video gets so much less likes and views💔💔