Vibronic spectra involve simultaneous changes in the vibrational and electronic energy states of a molecule.
 In the gas phase vibronic transitions are accompanied by changes in rotational energy also.
 Vibronic spectra of diatomic molecules have been analysed in detail; emission spectra are more complicated than absorption spectra.
 The intensity of allowed vibronic transitions is governed by the Franck–Condon principle.
 Vibronic spectroscopy may provide information, such as bond-length, on electronic excited states of stable molecules.
 It has also been applied to the study of unstable molecules such as dicarbon, C, in discharges, flames and astronomical objects.
In molecular physics, the molecular term symbol is a shorthand expression of the group representation and angular momenta that characterize the state of a molecule, i.e. its electronic quantum state which is an eigenstate of the electronic molecular Hamiltonian.
 It is the equivalent of the term symbol for the atomic case.
 However, the following presentation is restricted to the case of homonuclear diatomic molecules, or other symmetric molecules with an inversion centre.
 For heteronuclear diatomic molecules, the "u/g" symbol does not correspond to any exact symmetry of the electronic molecular Hamiltonian.
 In the case of less symmetric molecules the molecular term symbol contains the symbol of the group representation to which the molecular electronic state belongs.
Zero differential overlap is an approximation in computational molecular orbital theory that is the central technique of semi-empirical methods in quantum chemistry.
 When computers were first used to calculate bonding in molecules, it was possible to only calculate diatomic molecules.
 As computers advanced, it became possible to study larger molecules, but the use of this approximation has always allowed the study of even larger molecules.
 Currently semi-empirical methods can be applied to molecules as large as whole proteins.
 The approximation involves ignoring certain integrals, usually two-electron repulsion integrals.
 If the number of orbitals used in the calculation is N, the number of two-electron repulsion integrals scales as N.
 After the approximation is applied the number of such integrals scales as N, a much smaller number, simplifying the calculation.
Mark Douglas Havey from the Old Dominion University, was awarded the status of Fellow in the American Physical Society, after they were nominated by their Division of Atomic, Molecular & Optical Physics in 1998, for "development and explication of novel one- and two-photon spectroscopies of bound and dissociative electronic states of diatomic molecules; also for development of precision atomic two-photon polarization spectroscopy for determination of atomic matrix elements and novel sum rule."
Friedrich Hermann Hund (4 February 1896 – 31 March 1997) was a German physicist from Karlsruhe known for his work on atoms and molecules.
A molecular orbital diagram, or MO diagram, is a qualitative descriptive tool explaining chemical bonding in molecules in terms of molecular orbital theory in general and the linear combination of atomic orbitals (LCAO) molecular orbital method in particular.
 A fundamental principle of these theories is that as atoms bond to form molecules, a certain number of atomic orbitals combine to form the same number of molecular orbitals, although the electrons involved may be redistributed among the orbitals.
 This tool is very well suited for simple diatomic molecules such as dihydrogen, dioxygen, and carbon monoxide but becomes more complex when discussing even comparatively simple polyatomic molecules, such as methane.
 MO diagrams can explain why some molecules exist and others do not.
 They can also predict bond strength, as well as the electronic transitions that can take place.
Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements.
 The prefix "di-" is of Greek origin, meaning "two".
 If a diatomic molecule consists of two atoms of the same element, such as hydrogen (H) or oxygen (O), then it is said to be homonuclear.
 Otherwise, if a diatomic molecule consists of two different atoms, such as carbon monoxide (CO) or nitric oxide (NO), the molecule is said to be heteronuclear.
David DeMille is an American physicist and Professor of Physics at Yale University.
 He is best known for his use of polar diatomic molecules to amplify symmetry-violating effects within the molecules and as a means for manipulating the external properties of the molecules.
Homonuclear molecules, or homonuclear species, are molecules composed of only one type of element.
 Homonuclear molecules may consist of various numbers of atoms, depending on the element's properties.
 Some elements form molecules of more than one size.
 Noble gases rarely form bonds, so they only have one atom.
 The most familiar homonuclear molecules are diatomic, meaning they consist of two atoms, though not all diatomic molecules are homonuclear.
 Homonuclear diatomic molecules include hydrogen (H), oxygen (O), nitrogen (N) and all of the halogens. Ozone (O) is a common triatomic homonuclear molecule.
 Homonuclear tetratomic molecules include arsenic (As) and phosphorus (P).
In rotational-vibrational and electronic spectroscopy of diatomic molecules, Hund's coupling cases are idealized cases where specific terms appearing in the molecular Hamiltonian and involving couplings between angular momenta are assumed to dominate over all other terms.
 There are five cases, traditionally notated with the letters (a) through (e).
 Most diatomic molecules are somewhere between the idealized cases (a) and (b).

Question:  What city was the birthplace of the German physicist for which Hund's coupling cases in the spectroscopy of diatomic molecules are name for?
Answer: Karlsruhe