The magnetic susceptibility of the cluster compounds Mo6Se8 and Mo6Te8 has been measured at temperatures between 82 and 330 K, using a Faraday balance. The paramagnetic and diamagnetic components of the susceptibility have been analyzed. The Pauli component was evaluated using the density of states at the Fermi level obtained by band structure calculations, while the core component was evaluate...

In October 1924, The Physical Review, a relatively minor journal at the time, published a remarkable two-part paper by John H. Van Vleck, working in virtual isolation at the University of Minnesota. Van Vleck used Bohr’s correspondence principle and Einstein’s quantum theory of radiation to find quantum formulae for the emission, absorption, and dispersion of radiation. The paper is similar but...

We use the technique of terahertz time-domain spectroscopy to investigate the absorption and dispersion of spectrally dense methyl halide vapors, particularly in the lowand high-frequency spectral wings. For the first time to our knowledge, it is possible to observe essentially zero-frequency absorption resulting from molecular tunneling between the two states of symmetry simultaneously, with a...

A unified viewpoint on the van Vleck and Herman-Kluk propagators in Hilbert space and their recently developed counterparts in Wigner representation is presented. It is shown that the numerical protocol for the Herman-Kluk propagator, which contains the van Vleck one as a particular case, coincides in both representations. The flexibility of the Wigner version in choosing the Gaussians’ width f...

According to Heine (see Marden [l, §9], or Marden [2]),1 there exist some choices F(z) of the polynomial R(z) corresponding to each of which equation (1.1) has a polynomial solution S(z). The 5(z) were called Stieltjes polynomials by Van Vleck in honor of the man who first studied the location of their zeros relative to those of P(z). For a similar reason, we shall call the F(z) Van Vleck polyn...

in this paper. (1) we determine the complex-valued solutions of the following variant of van vleck's functional equation $$int_{s}f(sigma(y)xt)dmu(t)-int_{s}f(xyt)dmu(t) = 2f(x)f(y), ;x,yin s,$$ where $s$ is a semigroup, $sigma$ is an involutive morphism of $s$, and $mu$ is a complex measure that is linear combinations of dirac measures $(delta_{z_{i}})_{iin i}$, such that for all $iin i$,...