An algorithm allowing simulating vibrational spectra from classical time-dependent trajectories was applied for infrared absorption, vibrational circular dichroism, Raman, and Raman optical activity of model harmonic systems. The implementation of the theory within the TINKER molecular dynamics (MD) program package was tested with ab initio harmonic force fields in order to determine the feasib...

Time-resolved pump–probe spectra of 1,18,3,3,38,38-hexamethyl-4,48,5,58-dibenzo-2,28indotricarbocyanine ~HDITC!, a cyanine dye, in ethylene glycol are obtained using 11 fs and 90 fs duration pulses and analyzed in order to study its potential energy surfaces and vibrational dynamics. Ten oscillatory frequencies ranging from 30 cm to 1400 cm are observed in the 11 fs duration wavelength-resolved...

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...

The discrete nature of the vibrational modes of an isolated nanometer-scale solid dramatically modifies its low-energy electron and phonon dynamics from that of a bulk crystal. However, nanocrystals are usually coupled—even if only weakly so—to an environment consisting of other nanocrystals, a support matrix, or a solid substrate, and this environmental interaction will modify the vibrational ...

Received 9 September 2007; in final form 20 December 2007 Abstract The fundamental frequencies and the mean values of the internal coordinates are extracted from the trajectories of classical dynamics based on the relation between the classical and the quantum mechanical frequencies using quasi-classical direct ab initio molecular dynamics, where the oscillator amplitude is specified by setting...

• Table S6: Harmonic vibrational frequencies at the ωB97X-D/aug-cc-pVTZ level using SG-2 and SG-3. In this case, analytic Hessians are available in QChem so we compare these analytic results to frequencies computed via finite difference of analytic gradients. Results show that there is very little difference between the two approaches, which validates other finite-difference frequencies reporte...