Phase transitions for N-electron atoms at the large-dimension limit

PABLO SERRA; SABRE KAIS

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 1997 vol. 55 p. 238 - 247

1050-2947

Symmetry breaking of electronic structure configurations for N-electron atoms in weak magnetic and elec-tric fields at the large-dimension limit is described in terms of standard phase transitions. This symmetrybreaking, which leads to ionization, is completely analogous to phase transitions and critical phenomena instatistical mechanics. This analogy is shown by allowing the nuclear charge to play a role analogous totemperature in statistical mechanics. For the exact solution of N-electron atoms at the large-dimension limit,the symmetry breaking is shown to be a first-order phase transition. For the special case of two-electron atoms,the first-order transition shows a triple point where three phases with different symmetry coexist. Treatment ofthe Hartree-Fock solution reveals a different kind of symmetry breaking where second-order phase transitionsexist for N=2. We show that Hartree-Fock two-electron atoms in a weak external electric field exhibit acritical point with mean field critical exponents ( beta =1/ 2,  alpha= 0_dis , delta = 3, and gamma = 1).