Recent content by JMedley

  1. J

    Contraction of the Riemann Tensor with the Weak Field Metric

    Ok so that takes care of the factor 3, then how does \phi^{,i}_{,i} correspond to \nabla^2\phi ? Cheers for the help
  2. J

    Contraction of the Riemann Tensor with the Weak Field Metric

    I have started with the space-time metric in a weak gravitational field (with the assumption of low velocity): ds^2=-(1+2\phi)dt^2+(1-2\phi)(dx^2+dy^2+dz^2) Where \phi<<1 is the gravitational potential. Using the standard form for the Christoffel symbols have found: \Gamma^0_{00}=\phi_{,0}...
  3. J

    Contraction of the Riemann Tensor with the Weak Field Metric

    I have started with the space-time metric in a weak gravitational field (with the assumption of low velocity): ds^2=-(1+2\phi)dt^2+(1-2\phi)(dx^2+dy^2+dz^2) Where \phi<<1 is the gravitational potential. Using the standard form for the Christoffel symbols have found...
  4. J

    Density Functional Theory and the Local Density Approximation

    Well because we've been working in Rydberg units I thought the External potential was: -\frac{2Z}{r} In that case I think we may be summing the wrong energy; at the moment we're inputting an initial density of double the Hydrogen 1s density. We then use this to get a hartree potential and an...
  5. J

    Density Functional Theory and the Local Density Approximation

    Cool, So I've got it so that it converges on an energy (having used a simple mixing scheme). Unfortunately its the wrong energy! I've solved Possions equation in order to get the Hartree energy of the Helium atom and used the exchange-correlation functional of: V_{xv}[n(r)] =...
  6. J

    Density Functional Theory and the Local Density Approximation

    Ok, I guess I underestimated this one! Thus far I have an exchange-correlation term of: E_{xc}= -\frac{3}{4}\sqrt[3]{\frac{3n(r)}{\pi}}+\frac{0.44}{r_s+7.8} Where n(r) is the density of electrons and [ tex ] r_s [/tex] is the Wigner radius. Is this an acceptable expression? I have then...
  7. J

    Density Functional Theory and the Local Density Approximation

    As to what I'm trying to achieve: "I'm trying to calculate the ground state energy of Helium" As to how I plan on doing it: "density functional theory" And admittedly I wasn't particularly clear on the problems but in particular finding a reasonably accurate exchange-correlation term. I'd read...
  8. J

    Density Functional Theory and the Local Density Approximation

    Im trying to calculate the ground state energy of Helium using a density functional theory approach combined with the local density approximation. So far I have set up universal functionals and I mainly need help with the actual algorithm the evaluation of the Hartree energy functional.
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