Odbadrakh, Tuguldur, T.
(2018)
Applications of the Quantum Drude Oscillator Model for Dispersion Interactions and Vibrational Spectroscopy of Charged Water Clusters.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The harmonic oscillator model is used as the basis for describing dispersion interactions and
as the basis for computation of the vibrational frequencies of the hydronium ion at vari-
ous levels of hydration. First, configuration interaction, Rayleigh-Schrödinger perturbation
theory, and the random-phase approximation are applied to two quantum Drude oscillators
coupled through the dipole-dipole interaction. It is found that the RPA gives the exact
C 6 dispersion coefficient with only the first excited state included while the other methods
require infinite excited states. The dispersion-induced dipole moment is derived from the
dipole-dipole and dipole-quadrupole interactions between two Drude oscillators by computing
the dipole moment expectation value from the second-order wavefunction, and by an inte-
gral over the frequency-dependent polarizability and hyperpolarizability of the oscillators.
Finally, the correct C 6 coefficient is recovered from the dispersion-induced dipole moment
from the electrostatic Hellmann-Feynman theorem. Then secondly, the harmonic oscillator
model is used as the basis for computing the vibrational frequencies of cryogenically-cooled,
gas-phase H + (H 2 O) n=1,4,10,21 clusters. The OH stretching frequencies are found to red shift
dramatically due to the cubic coupling between the OH stretching modes and due to an
inductive interaction from the electric field of the hydration environment. Finally, the role
of the electric field in the proton-transfer mechanism in water is discussed.
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| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
| Creators | Email | Pitt Username | ORCID  |
|---|
| Odbadrakh, Tuguldur, T. | odt2@pitt.edu | odt2 | |
|
| ETD Committee: |
|
| Date: |
28 June 2018 |
| Date Type: |
Publication |
| Defense Date: |
10 April 2018 |
| Approval Date: |
28 June 2018 |
| Submission Date: |
4 April 2018 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
73 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
drude, vibrational spectroscopy, dispersion interactions, harmonic oscillator |
| Date Deposited: |
28 Jun 2018 18:37 |
| Last Modified: |
28 Jun 2018 18:37 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/34057 |
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