Geometric phase

Because of limitations of space, this section concentrates very little on rotational motion and its interaction with the vibrations of a molecule. However, this is an extremely important aspect of molecular dynamics of long-standing interest, and with development of new methods it is the focus of mtense investigation [18, 19, 20. 21. 22 and 23]. One very interesting aspect of rotation-vibration dynamics involving geometric phases is addressed in section A1.2.20. 

Kuppermann A and Wu Y S M 1993 The geometric phase effect shows up in chemical reactions Chem. 

Berry M 1990 Anticipations of the geometric phase Physics Today 43 34... 

Molecular aspects of geometric phase are associated with conical intersections between electronic energy surfaces, W(Q), where Q denotes the set of say k vibrational coordinates. In the simplest two-state case, the W Q) are eigen-surfaces of the nuclear coordinate dependent Hermitian electronic Hamiltonian... 

The presence of the half-odd quantum number j in Eq. (69) is potentially a physically measurable consequence of geomehic phase, which was first claimed to have been detected in the spectrum of Naa [16]. The situation is, however, quite complicated and the first unambiguous evidence for geometric phase in Nas was reported only in 1999 [17],... 

EARLY PERSPECTIVES ON GEOMETRIC PHASE Quadratic case lower surface... 

Mead and Truhlar [10] broke new ground by showing how geometric phase effects can be systematically accommodated in scattering as well as bound state problems. The assumptions are that the adiabatic Hamiltonian is real and that there is a single isolated degeneracy hence the eigenstates n(q-, Q) of Eq. (83) may be taken in the form... 

It is beyond the scope of these introductory notes to treat individual problems in fine detail, but it is interesting to close the discussion by considering certain, geometric phase related, symmetry effects associated with systems of identical particles. The following account summarizes results from Mead and Truhlar [10] for three such particles. We know, for example, that the fermion statistics for H atoms require that the vibrational-rotational states on the ground electronic energy surface of NH3 must be antisymmetric with respect to binary exchange... 

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