The PPEXSIDFTDriver routine and PPEXSIDFTDriver2 routines are standalone routines for solving the density matrix with the capability of finding the chemical potential effectively. This can be used for \(\Gamma\) point calculation. For electronic structure calculations with k-points, multiple Hamiltonian operators may be needed to compute the number of electrons. The PEXSI package provides expert level routines for such purpose. See driver_fermi_complex.c for an example of the components.