where | Y l m ⟩ ⟩ projects a one-particle wavefunction, such as one Kohn-Sham orbital, to the angular momentum labeled by { l , m } . V l m ( r ) is the pseudopotential that acts on the projected component. Different angular momentum states then feel different potentials, thus the HSC norm-conserving pseudopotential is non-local, in contrast to local pseudopotential which acts on all one-particle wave-functions in the same way.