Recent content by AA1983

Is it V=-2U\delta(x_{j}-x_{k})\delta_{\eta_{1}\Uparrow}\delta_{\eta_{2}\Downarrow}\delta_{\eta_{3}\Uparrow}\delta_{\eta_{4}\Downarrow} ?

In the Anderson model, it cost an energy Un_{\Uparrow}n_{\Downarrow} for a quantum dot level to be occupied by two electrons. Here n_{\Uparrow} is the second quantized number operator, counting the number of particles with spin \Uparrow. I need the term Un_{\Uparrow}n_{\Downarrow} in first...

Fredrik, thanks for your reply. I am trying to put it in the form (As)^T(BS) where A and B are matrices describing rotations. Taking B=identity, A will not be a rotation matrix (as far as I can see) since detA\neq0. I have (Zs)^T S where Z does not describe a rotation. This I want to put...

Hi, I have a problem identifying some 3d rotation matrices. Actually I don't know if the result can be brought on the desired form, however it would make sense from a physics point of view. My two questions are given at the bottom. \mathbf{s}=\left( \begin{array}{c} s_{x} \\ s_{y} \\ s_{z}...

Hi, I have a problem identifying some 3d rotation matrices. Actually I don't know if the result can be brought on the desired form, however it would make sense from a physics point of view. My two questions are given at the bottom. \mathbf{s}=\left( \begin{array}{c} s_{x} \\ s_{y} \\ s_{z}...