Rader, Caroline Anne (2019) Benchmark Structures and Harmonic Vibrational Frequencies of Hydrated Halide Ions: X– (H2O)n, X = F, Cl, Br, and I (where n = 1 – 4). Undergraduate thesis, under the direction of Greg Tschumper from Chemistry and Biochemsitry, The University of Mississippi.

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Abstract
This study extends our efforts to generate benchmark structures and harmonic vi brational frequencies from neutral hydrogen bonded clusters to solvated ions. The analytical gradients and Hessians developed for the Nbody:Manybody integrated QM:QM method facilitate the computation of benchmarkquality properties near the CCSD(T) complete basis set limit. In this work, a series of solvated halide ion sys tems (X−(H2O)n clusters, where X = F, Cl, Br and I and n = 1 to 4) is being characterized with the MP2 and 2body:Manybody CCSD(T):MP2 (2b:Mb) meth ods. For n ≥ 2, the latter technique uses the highlevel CCSD(T) method to evaluate all 1 and 2body interactions whereas the lowlevel MP2 method is used for the 3 body through Nbody terms of the manybody expansion. Triple and quadrupleζ quality correlationconsistent basis sets were used for these geometry optimizations and harmonic frequency computations. The relative energies, intermolecular OH· · · X bond distances and harmonic vibrational frequency shifts (from the H2O symmetric stretch) are reported for 10 different systems, some of which are found in previous literature and some of which are new structures. The intermolecular OH· · · X bond distances are larger for systems with a larger anion atom and for systems with more waters, and the harmonic vibrational frequency stretches are larger for systems with a smaller anion atom and for systems with fewer waters. Bond distance and vibrational frequency deviations (from benchmark values) demonstrate that method effects play a larger role than basis sets effects when describing these systems.
Item Type:  Thesis (Undergraduate) 

Creators:  Rader, Caroline Anne 
Student's Degree Program(s):  B.A. Biochemistry 
Thesis Advisor:  Greg Tschumper 
Thesis Advisor's Department:  Chemistry and Biochemsitry 
Institution:  The University of Mississippi 
Subjects:  Q Science > QD Chemistry 
Depositing User:  Caroline Rader 
Date Deposited:  10 May 2019 04:52 
Last Modified:  10 May 2019 04:52 
URI:  http://thesis.honors.olemiss.edu/id/eprint/1419 
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