We have obtained spectra of the high-lying vibrational levels of the ASu 1 and 1Sg states of both Li2 and Li2 via photoassociation of colliding ultracold atoms confined to a magneto-optical trap. Because of the low collision energies (;1 mK!, very high spectroscopic resolution is realized, and sensitivity is greatest for the usually difficult to access long-range states. Binding energies relati...

Using the core-mass approach, we have generated a vibrational-mass surface for the triatomic H3+. The coordinate-dependent masses account for the off-resonance nonadiabatic coupling and permit a very accurate determination of the rovibrational states using a single potential energy surface. The new, high-precision measurements of 12 rovibrational transitions in the ν2 bending fundamental of H3+...

Quantum mechanical ro-vibrational calculations are presented for the ArHC1 van der Waals complex using Hutson and Howard's empirical M5 potential. Analysis of the nodal structures, second differences and overlapping avoided crossings suggests that the higher bound states of ArHC1 are chaotic. This chaos is made evident by perturbing the angular part of the kinetic energy term, e.g. by isotopic ...

We investigate the OH stretch vibrational frequency shifts of a prototype photoacid, 2-naphthol (2N), when dissolved in solvents of low polarity. We combine femtosecond mid-infrared spectroscopy and a theoretical model based on the Pullin-van der Zwan-Hynes perturbative approach to explore vibrational solvatochromic effects in the ground S(0) and the first electronically excited (1)L(b) states....

We have calculated free energy and vibrational entropy differences in Ni3Al between its equilibrium ordered structure and a disordered fcc solid solution. The free energy and entropy differences were calculated using the method of adiabatic switching in a molecular-dynamics formalism. The path chosen for the free-energy calculations directly connects the disordered with the ordered state. The a...

Molecular distortion of dynamic molecules gives a clear signature in the vibrational spectra, which can be modeled to give estimates of the energy barrier and the sensitivity of the frequencies of the vibrational modes to the reaction coordinate. The reaction coordinate method (RCM) utilizes ab initio-calculated spectra of the molecule in its ground and transition states together with their rel...

In this series of studies, we systematically apply the analytical energy gradients of the direct symmetry-adapted cluster-configuration interaction singles and doubles nonvariational method to calculate the equilibrium geometries and vibrational frequencies of excited and ionized states of molecules. The harmonic vibrational frequencies were calculated using the second derivatives numerically c...

A theoretical approach has been developed to model the vibrational modes of amorphous, two-dimensional materials. The method considers that the vibrational density of states is composed primarily of states originating from embedded ring structures of medium-range order. The materials are modeled as continuous random networks comprised of a statistical distribution of symmetric, planar rings wit...

Resonant vibrational and rotation–vibration excitation cross sections for electron–CO scattering are calculated in the 0–10 eV energy range for all 81 vibrational states of CO, assuming that the excitation occurs via the 2 shape resonance. Static exchange plus polarization calculations performed using the R-matrix method are used to estimate resonance positions and widths as functions of intern...

Vibrational wavenumber assignments and geometrical parameters of single layer graphene (SLG) were investigated using density functional theory (DFT) with the basis set of 6-31G (d,p). The scaled vibrational assignments are found to be in good agreement with experimental values. The excitation energy, oscillator strength and wavelength were calculated using time dependent density functional theo...