Recent content by Qturtle

so if i understand you right, the example of a nonrelativistic string which its equation of motion is derived using the assumptions of small oscillation and that can not do much other then oscillate with constant tension, is just a privet case of the more general relativistic string (that can do...

thanks for the comment. how is this possible if the string has tension? if you need to assume small vibrations to derive the wave equation of stings, and then you build a lagrangian that gives you the wave equation, shouldn't the restrictions still be valid? please explain why do you say that...

Hey all. I've started to read and watch lectures on string theory. usually everyone starts with a classical relativistic particle action, and then goes to a classical relativistic string action. after they finish with the classical string they start the quantization process. my question is...

Hi. i have a 4x4 matrix \begin{pmatrix} 0 & 1 & 1 & 1\\ 1 & 0 & i & -i\\ 1 & -i & 0 & i\\ 1 & i & -i & 0\\ \end{pmatrix} it has 2 eigenvalues and i want to block diagonalize it into a 2x2 block diagonal matrix. i can't seem to find the proper way to do that. do i need to have a commuting matrix...

hey DrDu since i don't have a very good background on group theory (abstract math is not my strong suit.. \:), and since it looks like a more general subject, is there a more concentrated example that applies this method strictly to the problem at hand? (i.e changing the basis of a tight binding...

Hey I have a tight binding Hamiltonian of a BCC lattice which is a 4x4 matrix in k space (the 4 elements correspond to 4 atoms that are in a unit cell) I want to expand it for small k's around the symmetry points P or Gamma or H. I'm looking at a paper by J. L. Ma˜nes, PHYSICAL REVIEW B 85...

Hey I have a function of x,y,z and i want to have a 3D graph of it. i was thinking maybe there is a color option that corresponds with the value of the function, something like DensityPlot in Wolfram but in 3D instead of 2D. the result should look like a box filled with semi transparent color...

yes I can see now that this is more general. Thanks

It is if you understand why an exponent of a line integral of A(x) can transform a function of p to a function of p-eA(x)

Thanks DrDu i'm actually looking for a good derivation of the peierls substitution (Eq. 9 and rf. 16 in the first paper) I wasn't able to find the original paper of peierls though ):

Hi i'm looking for some references (prefer books) or explanations as to how one couple electrons so an EM field in a second quantized formalism tight binding model. from what i know, one need to replace the hopping parameter with the same parameter multiplied by an exponent of the line integral...