The static and dynamical properties of the neutral naphthalene molecule in its ground electronic state have been investigated using a tight-binding potential. This semiempirical method has allowed us to obtain static information concerning geometry and normal-mode frequencies. Tight-binding molecular dynamics coupled with an adiabatic switching procedure has also given information on the anharmonicity of the potential energy surface of such neutral aromatic molecule. Finally, the absorption spectrum of the neutral naphthalene molecule, prepared in its ground vibrational state, has been calculated from the Fourier transform of the dipole autocorrelation function and compared with the experimental data.

We assess the performance of colored-noise thermostats to generate quantum mechanical initial conditions for molecular dynamics simulations, in the context of infrared spectra of large polyatomic molecules. Comparison with centroid molecular dynamics simulations taken as reference shows that the method is accurate in predicting line shifts and band widths in the ionic cluster (NaCl)(32) and in the naphthalene molecule. As illustrated on much larger polycyclic aromatic hydrocarbons, the method also allows fundamental spectra to be evaluated in the limit of T = 0, taking into account anharmonicities and vibrational delocalization.