Cluster variation method continuous

Statistical mechanics methods such as Cluster Variation Method (CVM) designed for working with lattice statics are based on the assumption that atoms sit on lattice points. We extend the conventional CVM [1] and present a method of taking into account continuous displacement of atoms from their reference lattice points. The basic idea is to treat an atom which is displaced by r from its reference lattice point as a species designated by r. Then the summation over the species in the conventional CVM changes into an integral over r. An example of the 1-D case was done successfully before [2]. The similar treatments have also been done for... 

While the use of direct absorption methods has grown, indirect action spectroscopic methods continue to be widely and successfully used in the study of neutral molecular clusters. As mentioned earlier, there are two commonly used detection methods, mass spectrometers and bolometers. Because of the variety of mass-spectroscopic methods, there is an equally wide range of techniques used in neutral cluster spectroscopy. One of the oldest among these involves electron-impact mass spectrometry of a cw neutral beam combined with vibrational predissociation spectroscopy using a tunable cw or pulsed laser. The advent of continuously tunable infrared sources (such as color center lasers and LiNbOa optical parametric oscillators) allowed for detailed studies of size and composition variation in neutral clusters. However, fragmentation of the clusters within the ionizer of the mass spectrometer, severely limited the identification of particular clusters with specific masses. Isotopic methods were able to mitigate some of the limitations, but only in a few cases. 

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