Investigations of diffuse intermolecular electronic systems

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Title: Investigations of diffuse intermolecular electronic systems
Author: Muguet, Francis F.
Abstract: Diffuse intermolecular electronic systems , such as the hydrated electron or the immonia and water dimers , present both a theoretical and a practical computational challenge . The hydrated electron was discovered more than 25 years ago , yet there is still no consensus on an explanation of this phenomenon . A novel model is presented here whereby the hydrated electron consists in an itinerant dihydronium radical structure . Although electrostatically neutral , the itinerant radical is shown to behave as a negative charge carrier under the influence of an electric field . Within this perspective , the hydrated electron may be considered a quasiparticle . Contrary of the absence of agreement between many experiments and the old but still popular cavity model description , the energetics in the new model , are shown to be consistent with photophysical experimental data . In order to understand negatively charged water clusters , it is also proposed that a metastable bifurcated water dimer structure is able to bind an extra electron . Prior to our studies , no ab initio computations had been able to reproduce the experimental geometry of the ammonia dimer nor to predict a water dimer anion with Franck -Conden factors agreeing with those recently found in molecular beam experiments . In both cases the potential energy surface is determined by attractors corresponding to nonlinear and linear hydrogen bonded geometries , respectively . One attracter receives an unfair advantage in the computational procedure mainly because of the basis set superposition error (ESSE ) . There is still no agreement on a scheme for correcting the ESSE . A widely employed error estimation method is the counterpoise correction . A completely different new method is proposed using reerthonermalizatien of purified localized molecular orbitals . In terms of a ESSE corrected potential energy surface of the water dimer , a multi -attractor model of water is very briefly discussed . For further water molecular dynamics studies , we offer a new algorithm which we have developed specifically for a massively parallel computer .
URI: http : / /hdl .handle .net /2346 /21170
Date: 1992-05

Citation

Investigations of diffuse intermolecular electronic systems. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /21170 .

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