Stable and efficient quantum mechanical calculations with PUMA on triclinic lattices

In this paper we are concerned with the efficient approximation of the Schrödinger eigenproblem using an orbital-enriched flat-top partition of unity method on general triclinic cells. To this end, we generalize the approach presented in Albrecht et al. (Comput. Meth. Appl. Mech. Eng. 342:224-239, 2018) via a simple yet effective transformation approach and discuss its realization in the PUMA software framework. The presented results clearly show that the proposed scheme attains all convergence and stability properties presented in Albrecht et al. (Comput. Meth. Appl. Mech. Eng. 342:224-239, 2018).