see here

## Known typos and errors in the homeworks

• Note to tutors. Make sure you have the solutions for THIS year's homeworks. They are similar to last year but a few of the problems have changed and a few of the solutions have been improved.

• Question 5.5. Please interpret N as the number of unit cells per unit volume.

## Known errors from lectures

• Lecture 2: In the calculation explaining how to count modes in a box. We got to the form 3 V \int d3k / (2pi)^3. Then we converted to radial coordinates. The integral over dk should have been from k=0 to k=infinity. Somehow I put a k as the upper limit of integration. It was then corrected when we converted from k to frequency, as I did correctly write the upper limit of the frequency integral as infinity. <\li>

• Lecture 5: When doing the molecular orbital calculation we wrote down an effective schroedinger equation sum_j H_{ij} phi_j = E phi_i, where H_{ij} is a 2 x 2 matrix. Mistakenly I wrote sum_{ij}. Sorry about this! <\li>