Recent content by SadScholar

  1. S

    What's a general algorithm to build a supercell from a primitive cell?

    Basically, I've written some code that take as inputs 1)Basis vectors 2)lattice translation vectors and computes the structure factor of the basis, producing a diffraction pattern. I'd like to begin incorporating subtle differences between atoms, so I want to compute the structure factor of...
  2. S

    How does x-ray diffraction from different Bragg planes add up?

    It looks like I lied. I took the Debye-Waller factor into account, and the pattern showed up perfectly.
  3. S

    How does x-ray diffraction from different Bragg planes add up?

    Thanks for this. Does Rietveld fitting take this kind of thing into account?
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    How does x-ray diffraction from different Bragg planes add up?

    I'm writing a little bit of Mathematica code that should be able to make a reasonable powder diffraction spectrum. The algorithm is like this: Take Bravais lattice and basis. Compute reciprocal vectors. Compute structure factor (and its square magnitude) Have triple nested loop that creates...
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    LaTeX How can I put multiple line equations inside a box in Latex?

    kdv, thanks for posting your answer after finding it. Google funneled me here, and your post has helped me out.
  6. S

    What's a thorough QM book besides Dirac?

    Thanks. I ended up grabbing Messiah at the library. It was actually really helpful.
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    What's a thorough QM book besides Dirac?

    Thanks for the tip! I actually suspected it might be a graduate level text I was looking for.
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    What's a thorough QM book besides Dirac?

    Hi, PF. I've got a question for you. Maybe this would be better posted in the science education or discussion sections, but it's directly related to QM. I'm just finishing up my undergrad coursework and I've taken QM using Griffiths. It's an okay book, but it does a bit of jumping around, and...
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    Maths - a proof question on the nature of roots of quadratic equations

    The variable is ##x##, so make the given equation look like a regular quadratic in ##x##. Then pick off what ##a##, ##b##, and ##c## are and write the inequality for ##\Delta## in terms of those. It will quickly resolve into what's requested.
  10. S

    Separation of Variables for ODE

    I believe that's correct. And you can always plug your function for y back into the differential equation and make sure that it gives you a true statement.
  11. S

    Separation of Variables for ODE

    It's should be arctan(x). So $$ y'\arctan(x)-\frac{y}{1+x^2}=0\\ \Rightarrow \int \frac{\mathrm{d}y}{y}=\int \frac{1}{1+x^2}\frac{1}{\arctan(x)}\, \mathrm{d}x\text{.} $$ At this point it is helpful to note that $$ \frac{\mathrm{d}}{\mathrm{d}x}\arctan(x)=\frac{1}{1+x^2}\text{.} $$ So...
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    Motion equation for harmonic oscillator

    Careful, vela. You've got acceleration equal to force.
  13. S

    Feynman diagram tattoo suggestion

    There are some cool ones in here: http://homepage.mac.com/stevepur/physics/matter/matter.3.html http://oer.physics.manchester.ac.uk/NP/Notes/Notes/Notesse30.xht
  14. S

    Second Order Differential Equations

    $$ k=\pm i $$ So the general form of the solution is $$ Q_g(x)=c_1 e^{ix}+c_2 e^{-ix} $$ Or equivalently, $$ Q_g(x)=A\sin(x)+B\cos(x) $$ Now take a guess at the particular solution. Let's guess that ##Q_p(x)=D\sin(2x)##. Plug this into the differential equation and solve for D. It...
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