A contribution to stress-dependent vibration peaks : - Asymmetric stretching mode - Uniaxial loading

An interesting effect in silica glass is the shift of IR- and Raman-peaks
under externally applied stresses. A first interpretation of the influence of
stress on the IR frequency was made possible by its influence on the bond
angles, as had been shown very early by Galeener [1]. In this interpretation,
the stress effect is assumed as a consequence of a change of the bond
angles due to the stresses.
In the following section we will show that the angle stretching is not the
only effect that influences the position of the frequency of IR lines. The
present Report will address the change in the peak position under uniaxial
tension and compression in the so-called asymmetric stretching mode (AS).
For our computations we used Lennard-Jones potential.
From our computations, we have to expect decreased frequency under
tension and increased frequency under compression loading. This result is
in agreement with measurement by Tallant et al. [2].