Dealing with Convergence Problems - Quantum ESPRESSO
Dealing with Convergence Problems In the process of charge self-consistent calculation and structure relaxation, sometimes the pw.x calculation will reach the maximum number of iterations or exit with an error, which is a problem of non-convergence of the calculation. On the one hand, the convergence problem is a physical reason, that is, the calculation does not conform to reality, including: (1) Modeling is not in line with reality: the input atomic coordinates and element types are wrong; the calculation settings of symmetry. (2) The approximation used is unrealistic: pseudopotentials with good performance are a necessary condition for the realization of calculations; k-space sampling method for metals; magnetic, strong spin-orbit coupling; transition metal elements with localized d and f orbitals On-site Coulomb repulsion (Hubbard U or Hybrid functional); Van der Waals force of molecular crystals, etc.; dipole electric field of surface slab model, etc. These non-converg...