Franck-Condon Factors as Spectral Probes of Polaron Structure

We apply the Merrifield variational method to the Holstein molecular crystal model in D dimensions to compute non-adiabatic polaron band energies and Franck-Condon factors at general crystal momenta. We analyze these observable properties to extract characteristic features related to polaron self-trapping and potential experimental signatures. These results are combined with others obtained by the Global-Local variational method in 1D to construct a polaron phase diagram encompassing all degrees of adiabaticity and all electron-phonon coupling strengths. The polaron phase diagram so constructed includes disjoint regimes occupied by "small" polarons, "large" polarons, and a newly-defined class of "compact" polarons, all mutually separated by an intermediate regime occupied by transitional structures

Gravitomagnetic time delay and the Lense-Thirring effect in Brans-Dicke theory of gravity

We discuss the gravitomagnetic time delay and the Lense-Thirring effect in the context of Brans-Dicke theory of gravity. We compare the theoretical results obtained with those predicted by general relativity. We show that within the accuracy of experiments designed to measure these effects both theories predict essentially the same result.Comment: 10 pages Typeset using REVTE

Astrophysical S-factor for 16^{16}O+16^{16}O within the adiabatic molecular picture

The astrophysical S-factor for $^{16}$O + $^{16}$O is investigated within the adiabatic molecular picture. It very well explains the available experimental data. The collective radial mass causes a pronounced resonant structure in the S-factor excitation function, providing a motivation for measuring the $^{16}$O + $^{16}$O fusion cross section at deep sub-barrier energies.Comment: 5 pages, 2 figures, SOTANCP2008 Conference, Strasbourg, France, May 13-16, 2008, To appear in IJMP

Modeling of gas adsorption on graphene nanoribbons

We present a theory to study gas molecules adsorption on armchair graphene nanoribbons (AGNRs) by applying the results of \emph{ab} \emph{initio} calculations to the single-band tight-binding approximation. In addition, the effect of edge states on the electronic properties of AGNR is included in the calculations. Under the assumption that the gas molecules adsorb on the ribbon sites with uniform probability distribution, the applicability of the method is examined for finite concentrations of adsorption of several simple gas molecules (CO, NO, CO$_2$, NH$_3$) on 10-AGNR. We show that the states contributed by the adsorbed CO and NO molecules are quite localized near the center of original band gap and suggest that the charge transport in such systems cannot be enhanced considerably, while CO$_2$ and NH$_3$ molecules adsorption acts as acceptor and donor, respectively. The results of this theory at low gas concentration are in good agreement with those obtained by density-functional theory calculations.Comment: 7 pages, 6 figure