Recent content by jpr0

  1. J

    DC conductance in the presence of a time-dependent electric field

    I calculated the DC conductance of a 2DES in the presence of a time-dependent (periodic) electric field using the Boltzmann equation some time ago, and I'd like to verify the results numerically. Ideally I'd like to perform a computation along the lines of a recursive Green's function...
  2. J

    A tight biinding calcualtion of graphene like structure

    If you're comparing the results of a DFT calculation to a phenomenological nearest-neighbour tight-binding Hamiltonian then you should find that in the tight-binding band structure the conduction and valence bands are symmetric about the Dirac point (about the line E=0). From a DFT...
  3. J

    Is the Official Google Answer to this Controversial Interview Question Correct?

    0,0,0,0,1,0,0,1 is perfectly valid. This would correspond to sampling 2 families, the first one of which had 4 girls and one boy, and the second of which had 2 girls and 1 boy. Edit: I wasn't thinking of how to calculate this computationally, which is a fairly easy task. I'm just trying to cut...
  4. J

    Is the Official Google Answer to this Controversial Interview Question Correct?

    I think you can formulate an equivalent problem in the following way: You're given a binary string, x, of length N bits. Each bit in the string is chosen randomly from {0,1}, except the last bit of the string, whose value is always 1. Let z be the number of zeros occurring in x. What is the...
  5. J

    Why is the ground state always symmetric?

    Well, that demonstrates that the ground-state for the 1D Schroedinger equation in a piece-wise constant potential contains no nodes. If that's the OP's question then you can simply solve the SE and verify that the ground state indeed contains no nodes. If you want to prove that it's true in...
  6. J

    Why is the ground state always symmetric?

    Hi, I know this is an old thread, but I have a simple Hamiltonian whose ground state is anti-symmetric. H=\left[\begin{array}{cc}0 & \Delta\\\Delta & 0\end{array}\right]\,. Eigenstates and eigenenergies are: \psi_{\eta}=\left[\begin{array}{c}1\\...
  7. J

    MATLAB Saving Matrices Generated by Matlab Algorithm

    By the way to output matrices to file... outfile = fopen(int2str(i),'w'); dummy = fwrite(outfile,M,'float64'); fclose(outfile); This saves the matrix M as binary data to the file 'i'
  8. J

    MATLAB Saving Matrices Generated by Matlab Algorithm

    you need to use the function int2str mystr = int2str(i); alternatively if you want to make the file name "NAMEFILE-i" then you can use sprintf(mystr,'NAMEFILE-%i',i); you'll have to check the syntax of this though, i can't remember it exactly off-hand. note that %i in the second argument...
  9. J

    Viewing PF from Brand New Safari Browser on Macbook

    Noooo Macs are the dark side... They should be banned :P
  10. J

    What is the role of electrostatic force in Bernoulli's Principle?

    When I say "pressure" I'm talking about the tangential force extered on the pipe by the fluid divided by the surface area of the pipe. If I take an open pipe through which water is pumped, and then a closed pipe where the pressure is turned down until the pressure is equal to that of the first...
  11. J

    What is the role of electrostatic force in Bernoulli's Principle?

    Look at this way: you have 2 pipes, one open ended, one is closed. You're telling me that in the open ended pipe where there is a flow I can have exactly the same pressure as in the first pipe - despite the fact that the fluid is flowing (and that this in some way show's how a microscopic...
  12. J

    What is the role of electrostatic force in Bernoulli's Principle?

    Yes they can. If you have 2 identical pipes with 2 identical pressures, one with a moving fluid, while the other holds the same (but stationary) fluid, what can you say about the temperature of the fluids in each of the pipes? What does this tell you about the average velocity of a molecule in...
  13. J

    Fixing an Xbox360 with a towel

    Maybe it was too cold to begin with :P
  14. J

    Downloading & Installing MiKTeX for University Reports

    First of all choose "download MikTex". As far as I understand it, MikTex is just a windows port of latex. You're probably best off just downloading the basic package - you can later on set MikTex to download packages when it needs them. After it's downloaded, rerun the installer, then choose...
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