Distortion energy, magnitude

Y ater dimer distance variation provides a sequence of structures for water dimer at different nonbonded OH distances. Plot energy (vertical axis) vs. nonbonded OH distance (horizontal axis). What is the optimum distance How much energy is required to increase this distance by 10% How much is required to reduce the distance by 10% Are the two distortion energies about the same magnitude If not, explain why not. 

The concept of distortional energy as a measure for the critical magnitude of the stress state a material can endure at a point in an elastic material (von Mises criterion) cannot be carried over directly to viscoelastic materials because viscoelastic deformation involves dissipative mechanisms. Thus, at any point in time the energy balance must be written as. 

Based on the above estimate, we can express the magnitude of distortion energy per molecule ... 

The vibrational relaxation of simple molecular ions M+ in the M+-M collision (where M = 02, N2, and CO) is studied using the method of distorted waves with the interaction potential constructed from the inverse power and the polarization energy. For M-M collisions the calculated values of the collision number required to de-excite a quantum of vibrational energy are consistently smaller than the observed data by a factor of 5 over a wide temperature range. For M+-M collisions, the vibrational relaxation times of M+ (r+) are estimated from 300° to 3000°K. In both N2 and CO, t + s are smaller than ts by 1-2 orders of magnitude whereas in O r + is smaller than t less than 1 order of magnitude except at low temperatures. 

The relative magnitude of both second-order terms determines whether the molecule is stable with respect to distortion along the vibrational coordinate Qt. If the relaxation term is of larger magnitude than the distortion term then the geometry is unstable and the potential energy surface has negative curvature for mode Qi. 

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