Solid Body Rotation Vibration

On Quaternions and the Rotation of a Solid Body

Centripetal focusing of gyrotactic phytoplankton in solid-body rotation

A suspension of gyrotactic microalgae Chlamydomonas augustae swimming in a cylindrical water vessel in solid-body rotation is studied. Our experiments show that swimming algae form an aggregate around the axis of rotation, whose intensity increases with the rotation speed. We explain this phenomenon by the centripetal orientation of the swimming direction towards the axis of rotation. This cent...

Vibration–rotation transition dipoles from first principles

The use of ab initio methods to calculate line positions and associated transition intensities for the infra-red spectrum of small molecules has recently become common. The first principles calculation of transition dipoles, upon which the intensity is based, relies on three distinct steps: the quantum chemical calculation of the dipole moment surface at a grid of geometries, the accurate repre...

Rotation Vibration Spectrum of the HCl Molecule

One might expect that quantum mechanical calculations capable of predicting the structure of even the simplest molecules would be quite complex. Indeed, solving the Schrödinger equation for the nuclei and all electrons would be a formidable task. Fortunately, this is not always necessary. Because of their large mass difference, accurate results can be obtained while treating the electron and nu...

Calculating the vibration–rotation spectrum of water

The spectrum of water is ubiquitous and therefore the demand for a reliable theoretical model for it remains pressing. The treatment of nuclear motion using methods based on the variational principle has led to a major advance in the development of the model but places great emphasis on the accurate treatment of the underlying potential energy surface. Progress in constructing high-accuracy pot...