The second reason is that calculated values are harmonic frequencies while the experimental values contain anharmonic
X-ray absorption fine structure (XAFS) has developed into a powerful probe of atomic structure, thermodynamic properties, and anharmonic
effects in atomic vibration of substances [1-28].
vibrational spectra of hydroxylamine and its 15N, 18O, and deuterium substituted analogs," Spectrochimica Acta--Part A Molecular and Biomolecular Spectroscopy, vol.
The third term is a harmonic term and the fourth is an anharmonic
term and they are responsible also for quark confinement.
To model this motion each base of a strand is assumed to be coupled with the next-neighbour bases of the same strand by the elastic backbone restoring forces and with the complementary base in the opposite strand by the anharmonic
potential used to model the hydrogen bond.
Jan, "Frequency and zero-point vibrational energy scale factors for double hybrid density functional (and selected other methods): can anharmonic
force fields be avoided?," Journal of Physical Chemistry A, vol.
However, since by hypothesis (8) the values of the frequency of oscillations w lie outside the range of the linear (phonon) band, the corresponding orbits are anharmonic
. This necessitates amplitude-depending tuning of the frequency so that the latter comes to lie outside of the phonon spectrum.
However, due to the anharmonic
feature of vibrations, the combination bands appear at a wavenumber that is higher than the sum of the fundamental bands .
Shi, "Aubry-Mather sets for relativistic oscillators with anharmonic
potentials," Acta Mathematica Sinica, vol.
The stress-strain relation of higher harmonic generation for a hyperelastic material is obtained from the nonlinear governing equations of Murnaghan model, which has a qualitative description of anharmonic
vibration, and the strain energy function W(E) is