Theoretical Studies of the Vibrational Spectra and Relaxation Dynamics of Ice and Water Open Access

Liu, Hanchao (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/fn106z825?locale=en
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Abstract

Recently, theoretical studies of condensed phase water have been advanced in two-fold, with the development of first the Wang-Huang-Braams-Bowman(WHBB) ab initio potential energy(PES) and dipole moment surfaces(DMS), and second the quantum Local-Monomer Model. The WHBB PES accurately describes the electronic energy of arbitrary number of water monomers using a many-body representation. The important intrinsic 2-body and 3-body interactions are permutationally invariant fits of tens of thousands ab initio energies. Very recently, a new dipole moment surface is reported using a spectroscopically accurate 1-body DMS and an intrinsic 2-body DMS fit. The quantum Local-Monomer Model uses a divide-and-conquer strategy and solves the Schrodinger equation for each water monomer embedded in its hydrated environment. This approach effectively reduces the formidable dimensionality of the condensed phase water to usually 3 to 6 and up to 9 degrees of freedom. The first half of the dissertation will review and formulate the WHBB PES and DMS and the Local-Monomer Model.

In the second half of the dissertation, we take advantage of this recent theoretical advancement and report several fully ab initio quantum studies of the vibrational spectra and dynamics of ice, liquid water and water hexamer. The topics include the infrared spectra of ice Ih and amorphous ice, vibrational density of states of neat and deuterated ice Ih and vibrational energy relaxation dynamics of HOD diluted ice, the infrared spectra of liquid water, and the infrared spectra and harmonic zero-point energies of HOD doped water hexamers.

Table of Contents

1. Introduction 1
2. Ab Initio Potential Energy and Dipole Moment Surfaces 16
2.1. Potential Energy Surface 16
2.2. Dipole Moment Surface 18
2.2.1. The WHBB Dipole Moment Surface 18
2.2.2. The New Dipole Moment Surface 20
2.2.3. Tests of the New DMS 22
3. The Quantum Local-Monomer Model 42
3.1. Overview 42
3.2. Theory 44
3.3. Extension 1: LMon-4 47
3.4. Extension 2: LMon-6 and Wave Packet Dynamics 50
3.5. Tests and Comparisons 51
3.5.1. Local Harmonic Analysis 51
3.5.2. Compare Local-Monomer Model with Other Methods for Vibrational Spectra in the Condensed Phase 53
4. The Vibrational Spectra and Relaxation Dynamics of Ice 66
4.1. Infrared Spectra of Ice Ih and Amorphous Solid Water 66
4.1.1. Overview 66
4.1.2. Ice Models 68
4.1.3. Infrared Spectra 71
4.1.4. Summary 78
4.2. Vibrational Density of States of Ice Ih 79
4.2.1. Overview 79
4.2.2. Full Normal Mode Analysis 83
4.2.3. Results and Discussion 83
4.2.4. Summary 97
4.3. Vibrational Energy Relaxation of Dilute HOD in Ice Ih 98
4.3.1. Overview 98
4.3.2. Computational Details 100
4.3.3. Vibrational Relaxation Lifetimes and Pathways 102
4.3.4. Summary 106
5. The Infrared Spectra of Liquid Water 114
5.1. Overview 114
5.2. Computational Details 117
5.3. Results and Discussion 118
5.4. Summary 136
6. Water Hexamer 140
6.1. Overview 140
6.2. HOD Doped Cage and Prism Hexamer 143
6.3. IR Spectra of Prism and Cage HOD(D2O)5 144
6.4. Harmonic Zero-Point Energies of Isotopomers of Prism and Cage HOD(D2O)5 155
6.5. Summary 159

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