The  restoration of the single-valuedness of the electron wavefunction for triatomic molecules by Mead and Truhlar was  achieved using this as-yet undiscovered factor.
This quantity causes the change in sign of the electronic wave function discovered by Herzberg and Longuet-Higgins. The  restoration of the single-valuedness of the electron wavefunction for triatomic molecules by Mead and Truhlar was  achieved using this as-yet undiscovered factor. This quantity was shown to be an element from the holonomy group for a  fibre bundle with a certain connection by Barry (*) Simon. It equals one-half the solid angle subtended at the origin by the  closed loop traced by a time-varying magnetic field for a spin one-half particle. This quantity is acquired by the instantaneous  eigenstate of a quantum system described by a cyclic time-dependent Hamiltonian, depends on the topology of the parameter  space, and is in addition to the dynamical phase. For 10 points, name this factor commonly seen in the Aharonov-Bohm effect.
This quantity causes the change in sign of the electronic wave function discovered by Herzberg and Longuet-Higgins.
Pancharatnam-Berry phase [or geometric phase; prompt on Pancharatnam phase]