@article {2017,
	title = {Self-adjoint realisations of the Dirac-Coulomb Hamiltonian for heavy nuclei},
	number = {SISSA;26/2017/MATE},
	year = {2017},
	abstract = {We derive a classification of the self-adjoint extensions of the
three-dimensional Dirac-Coulomb operator in the critical regime of the
Coulomb coupling. Our approach is solely based upon the KreIn-Vi{\v s}ik-
Birman extension scheme, or also on Grubb{\textquoteright}s universal classification
theory, as opposite to previous works within the standard von Neu-
mann framework. This let the boundary condition of self-adjointness
emerge, neatly and intrinsically, as a multiplicative constraint between
regular and singular part of the functions in the domain of the exten-
sion, the multiplicative constant giving also immediate information on
the invertibility property and on the resolvent and spectral gap of the
extension.},
	url = {http://preprints.sissa.it/handle/1963/35287},
	author = {Matteo Gallone and Alessandro Michelangeli}
}
