Interpretation of decreasing peak-shift for Raman-peaks in silica

A first interpretation of the influence of stress on the IR- and the Raman-
peak frequencies was made possible via its influence on the binding angles.
The stress effect was assumed as a consequence of a change of the bond
angles due to the stresses.
In addition we could show that the angle stretching is not necessarily the
only effect that influences the position of the frequency of IR lines. We
addressed the change in the peak position under uniaxial tension and com-
pression in computations using the Lennard-Jones potential.
From our computations, we have to expect decreasing frequency under ten-
sion and increasing frequency under compression loading. In our opinion,
this contribution of frequency shift has to be added to the contribution by
the angle stretching.