@article {2017,
	title = {Self-Adjoint Extensions of Dirac Operator with Coulomb Potential},
	number = {SISSA;09/2017/MATE},
	year = {2017},
	institution = {SISSA},
	abstract = {In this note we give a concise review of the present state-of-art for the
problem of self-adjoint realisations for the Dirac operator with a Coulomb-like singular
scalar potential V(x) = {\O}(x)I4. We try to follow the historical and conceptual
path that leads to the present understanding of the problem and to highlight the
techniques employed and the main ideas. In the final part we outline a few major
open questions that concern the topical problem of the multiplicity of self-adjoint
realisations of the model, and which are worth addressing in the future.},
	url = {http://urania.sissa.it/xmlui/handle/1963/35273},
	author = {Matteo Gallone}
}
@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}
}
