Eq. 19 in this paper gives the following Hamiltonian: $\sigma_a, \tau_a, \eta_a$ are respectively the spin, sublattice pseudospin and valley pseudospin respectively. Normally, I would have chosen a basis convention such as $\sigma_a, \tau_a, \eta_a$ and plugged in the $2\times 2$ identity matrix...

I'm interested in computing first and second derivatives of molecular Hamiltonians with respect to nuclear coordinates. I've been using Psi4 and PySCF to perform Hartree-Fock calculations, and I was wondering if there is any way to use these packages (or similar Python packages) to compute first ...

I have recently started to use Quantum ESPRESSO for evaluating different properties of ZnSe Quantum Dots. But I currently don't have access to any cluster and as I am increasing the size of calculation, my computer starts to hang and then crashes. Would it be feasible to create my own small clust...