CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

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CHAPTER 6 Structure, Energetics and Spectra of Ammonia Embedded Neutral Clusters 6.1. Introduction Up to chapter 5, discussions have been carried about microhydration of neutral halogen molecule, X 2 (X=Cl, Br & I) and anionic non-spherical species, Y (Y= Cl 2 •− , Br 2 •− , I 2 •− , CO 3 •− , NO 3 − and CO 3 2− ). This chapter describes about microsolvation of solute in a less polar medium like ammonia. In recent years, hydrogen bonded cluster of polar solvent molecules encapsulating a solute atom, small molecule or ion have been a subject of intense investigations for experimental as well as theoretical research. If a solute is immersed into a hydrogen bonded solvent medium, preexisting solvent network breaks up to accommodate the solute and a new hydrogen bonded network forms surrounding the solute. Ammonia is also an important solvent that can form hydrogen bonded network. The clusters of alkali metal atom and polar solvent molecules have been studied at length, often from the interests related to solvated electron. However, the detailed mechanism on the formation of solvated electron in this medium with alkali metal atom is not yet fully understood. Thus, solvated electron in polar solvents has been a subject of continued research. In this respect, a lot of research has been carried out to understand the structure and properties of singly negatively charged clusters of water and 94
ammonia. 61-62 Hydrogen bonded water clusters with alkali metal atom residing in the cluster cavity (M.nH 2 O) have also been studied to a great extent. 63-67,17 Solvated electrons can form rather readily with the alkali metals in polar solvent because of the relatively low energy requirement for ionization. The most familiar case occurs in the solvent stabilization of alkali metal atoms in bulk ammonia, where optical transitions involving these electrons are responsible for the strong colors of the resulting solutions. The formation of solvated electron in finite size clusters is also expected. A number of theoretical and experimental efforts have been put to gather knowledge on ammonia clusters in presence of Li, Na and Cs alkali metal atoms in the context of solvated electron. 16-17,66-72 In this chapter, structure, energy parameters and IR spectra of ammonia clusters in presence of a potassium metal atom (K.nNH 3 , n=1-6) based on first principle electronic structure theory is presented to study the process of microsolvation in ammonia medium. Studies on these size selected clusters play a critical role to follow the evolution of molecular level properties with the size of the cluster in gas phase and to bridge the gap between the properties of single ammonia cluster (K-NH 3 ) to the bulk solution of K metal in ammonia solvent. The variation of calculated properties with size (n) of the clusters, K.nNH 3 is also reported. As a number of minimum energy structures are predicted for higher cluster, weighted average properties of the clusters are calculated based on the statistical population of different minimum energy structures at 150 K. 6.2. Theoretical Approach Full geometry optimization of ammoniated clusters has been carried out without any symmetry restriction to locate minimum energy structures applying a nonlocal hybrid 95
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MICROSOLVATION OF CHARGED AND NEUTR
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STATEMENT BY AUTHOR This dissertati
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Dedicated to my Daughter, Wife and
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CONTENTS Page No. SYNOPSIS LIST OF
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CHAPTER 4 Solubility of Halogen Gas
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7.3.4. IR and Raman Spectra 117-121
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S Macroscopic Microscopic Dual leve
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molecular level interaction during
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Chapter 3: This chapter describes I
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In this system the conformers of a
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LIST OF FIGURES Page No. Fig. 1.1 2
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Fig. 2.6 54 (I) Plot of calculated
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(IIIA) Cl 2 .3H 2 O; (IIIB) Br 2 .3
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Fig. 6.3 104-105 Calculated scaled
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LIST OF TABLES Page No. Table. 2.1
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CHAPTER 1 Introduction 1.1. Microso
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1.2. Motivation 1.2.1. Macrosolvati
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ulk water and pure neutral water cl
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insight about the electronic struct
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Newton -Raphson (NR) method expand
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potential energy surface for these
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terms, the energy can be written in
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Boyd proposed the use of Gaussian t
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eported experimental findings. Theo
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hydrated halide series, X¯.nH 2 O,
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anions (Cl •− 2 , Br •− 2 &
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geometrical parameters close to MP2
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symmetrical DHB, SHB or WHB arrange
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of I-I axis and having the least I-
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Br •− 2 .nH 2 O hydrated cluste
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VI-F VI-G VII-A VII-B VII-C VII-D V
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To see the effect of hydration on t
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Five minimum energy structures disp
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arrangements. In total, it has one
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NO 3 − .nH2 O (n ≥ 6), a few eq
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V-E V-F V-G V-H V-I VI-A VI-B VI-C
Page 73 and 74: VII-D VII-E VII-F VII-G VII-H VII-I
Page 75 and 76: VIII-K VIII-L Fig.2.2. Fully optimi
Page 77 and 78: clusters. Hydrated cluster having c
Page 79 and 80: However, these calculations do not
Page 81 and 82: Table 2.1. Weighted average energy
Page 83 and 84: Where, E[I •− 2 .nH 2 O] is the
Page 85 and 86: The variation of the weighted avera
Page 87 and 88: CHAPTER 3 IR Spectra of Water Embed
Page 89 and 90: ecome more meaningful. At present,
Page 91 and 92: I-A II-A II-B III-A III-B III-C III
Page 93 and 94: Cluster experiments are carried out
Page 95 and 96: 3350-3500 cm -1 (scaling factor ~0.
Page 97 and 98: these systems, X. nH 2 O (X= Br 2
Page 99 and 100: CHAPTER 4 Solubility of Halogen Gas
Page 101 and 102: including polarized and diffuse fun
Page 103 and 104: and I 2 systems. The most stable st
Page 105 and 106: Cl Cl Br Br I I VA VB VC Cl Cl Br B
Page 107 and 108: (Br δ+ -Br δ- ) in the studied hy
Page 109 and 110: stabilization energy does not follo
Page 111 and 112: 80 Cl 2 .nH 2 O (n=1-8) 80 Br 2 .nH
Page 113 and 114: separated ion pair in presence of s
Page 115 and 116: adical ( • OH) reacts with HCO 3
Page 117 and 118: most stable conformer for each size
Page 119 and 120: The structures of the hydrated clus
Page 121 and 122: Table 5.1. Calculated absorption ma
Page 123: molar extinction coefficient value
Page 127 and 128: stable minimum energy structure is
Page 129 and 130: IV-A IV-B V-A V-B V-C VI-A VI-B VI-
Page 131 and 132: 6.3.3. Vertical Ionization Potentia
Page 133 and 134: 311++G(2d,2p) level, the scaling fa
Page 135 and 136: K(NH 3 ) 4 K(NH 3 ) 5 IR Intensity
Page 137 and 138: CHAPTER 7 Structure, Energetics and
Page 139 and 140: Thus Monte Carlo based simulated an
Page 141 and 142: I I I I I I I I A B C D I I I I I I
Page 143 and 144: interaction as well as solvent-solv
Page 145 and 146: Table 7.1. Various energy parameter
Page 147 and 148: change in VDE is observed. This is
Page 149 and 150: symmetric C-O stretching mode of CO
Page 151 and 152: to the maximum charge transfer of t
Page 153 and 154: CHAPTER 8 A Generalized Microscopic
Page 155 and 156: possible breakdown of these laws ma
Page 157 and 158: P 7 P , , P , ,, 1 ∂ 2
Page 159 and 160: M DE = (r, ω)C DE , (r,
Page 161 and 162: known. However, for most of the com
Page 163 and 164: The calculated bulk detachment ener
Page 165 and 166: espect to experimentally measured v
Page 167 and 168: References 1. Ohtaki, H.; Radani, T
Page 169 and 170: 29. Turi, L.; Sheu, W.; Rossky,P.J.
Page 171 and 172: 61. (a) Ehrler, O. T.; Neumark, D.
Page 173 and 174: LIST OF PUBLICATIONS *1. “σ/σ
Page 175 and 176:
13. “Vibrational analysis of I
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CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

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