Evolution of the vibrational spectra of doped hydrogen clusters with pressure

Abstract

The evolution of the vibrational spectra of the isoelectronic hydrogen clusters H26, H24He, and H24Li(+) is determined with pressure. We establish the vibrational modes with collective character common to the clusters, identify their individual vibrational fingerprints and discuss frequency shifts in the giga-Pascal pressure region. The results are of interest for the identification of doping elements such as inert He and ionic Li(+) in hydrogen under confinement or, conversely, establish the pressure of doped hydrogen when the vibrational spectrum is known. At high pressure, the spectra of the nanoclusters resemble the spectrum of a solid, and the nanoclusters may be considered crystals of nanometer scale. The computations are performed at the gradient-corrected level of density functional theory. The investigation is the first of its kind.

Recent progress in confined atoms and molecules: Superintegrability and symmetry breakings

“…In 6, the subsection borrows the title of [10] and illustrates its basic idea with the series of articles [72][73][74][75][76][77][78] on "Endohedral confinement of molecular hydrogen", "The atomization process of endohedrally confined hydrogen molecules", "Pressure and size effects in endohedrally confined hydrogen clusters", "Thermal behavior of a 13molecule hydrogen cluster under pressure", "Thermodynamic states of Nanoclusters at low pressures and low temperature: the case of 13H 2 , Evolution of the vibrational spectra of doped hydrogen clusters with pressure", "Pressure Induced metallization of Li + -Doped Hydrogen Clusters". The series has also common features with [12] considering Hydrogen fullerene cages instead of the familiar ones with Carbon, and also different species of confined systems and different processes.…”

“…(77), describes a 3-dimensional system which is separable in its transverse and axial components, Eqs. (78) and (79); the transverse potential V (x, y) confines the electron to the interval 0 < z < R, and the solutions of Eq. (78) via its eigenvalues λ convert Eq.…”

“…In [78], the "evolution of the vibrational spectra of the isolectronic hydrogen clusters H 26 , H 24 He and H 24 Li + with pressure" was investigated. The vibrational modes with collective character common to the clusters were frequency shifts in the GPa region were discussed.…”

Microscopic pressure-cooker model for studying molecules in confinement

“…Then, by following standard rules of analytical mechanics, the Lagrangian equations of motion are obtained. The model provides a formal framework for the previous studies of the hydrogen gas under the effects of pressure and temperature [4][5][6][7][8][9][10][11]. Contrary to other proposed models, the present model includes a representation of the medium surrounding the system of the confined particles by a direct inclusion of such properties as the structure and rigidity of the container, the viscosity of the fluid forming the surrounding medium, etc., described in terms of mechanical and statistical mechanics axioms.…”