  In this paper we present the generalized phase separation diagram for quantum
plasmas revealing the fundamental mechanism called the spontaneous core
collapse (SCC) for a white dwarf star core-density based on the extended
Shukla-Eliasson force for relativistically degenerate matter taking into
account the most important electron interaction features such as Fermi-Dirac
statistical pressure, Coulomb, exchange-correlation and quantum tunneling
effects. A critical core mass-density value is reported for white dwarf stars
beyond which the SCC mechanism will be inevitable. It is revealed that the SCC
critical core-density value is slightly affected by the ion charge state, $Z$
(the core composition). Such fundamental effect which is mainly caused by the
electron quantum diffraction effect can progressively lead the white dwarf star
with a mass beyond the Chandrasekhar limit through SCC, core fusion and the
ultimate supernova stages.
