  The electron spectrum in a uniform nanowire with a hexagonal cross-section is
calculated by means of a numerical diagonalization of the effective-mass
Hamiltonian. Two basis sets are utilized. The wave-functions of low-lying
states are calculated and visualized. The approach has an advantage over mesh
methods based on finite-differences (or finite-elements) schemes: non-physical
solutions do not arise. Our scheme can be easily generalized to the case of
multi-band (Luttinger or Kane) ${\bf k}\cdot{\bf p}$ Hamiltonians. The external
fields (electrical, magnetic or strain) can be consistently introduced into the
problem as well.
