Atmospheric Implications for Formation of Clusters of Ammonium and 1−10 Water Molecules

Abstract

A mixed molecular dynamics/quantum mechanics model has been applied to the ammonium water clustering system. The use of the high level MP2 calculation method and correlated basis sets such as aug-cc-pVDZ and aug-cc-pVTZ lends confidence in the accuracy of the extrapolated energies. These calculations provide electronic and free energies for the formation of clusters of ammonium and one to ten water molecules at two different temperatures. Structures and thermodynamic values are in good agreement with previous experimental and theoretical results. The estimated concentration of these clusters in the troposphere was calculated using atmospheric amounts of ammonium and water. Results show the favorability of forming these clusters and implications for ion-induced nucleation in the atmosphere.

Interaction between PH3 and small water clusters: Understanding the electronic and spectroscopic properties

“…No frequency scale factor was used for the vibrational frequencies or the zero-point vibrational energy (ZPVE). It is important to note that the studied phosphine-water structures are based on the analogous ammonium complexes [11][12][13][14][15][16][17][18][19].…”

“…Recently, Lane and Kjaergaard [11] also characterized the phosphine-water complex at a high level of theory using the CCSD(T)-F12 and CCSD(T) methods. For the analogous ammonium-water clusters [NH 3 (H 2 O) n ], a very different picture emerges due to the rich source information on these complexes [12][13][14][15][16][17][18][19][20][21]. The limited information on phosphine-water complexes due to a lack of any experimental data emphasizes the need to evaluate the electronic properties of the interaction between phosphine and more than one water molecule.…”

Pressure and temperature dependence on the hydrogen bonding and dynamics of ammonium ion in liquid water: A molecular dynamics simulations study

“…Also, in many natural and agricultural ecosystems, NH 4 + ion is the predominant nitrogen source and an important micronutrient in the world's water system [1]. Hence, a detailed understanding of the solvation process of ammonium ion plays an important role both in chemistry and biology and the subject of extensive experimental [2][3][4][5][6][7][8][9][10] and theoretical [11][12][13][14][15][16][17][18][19][20] studies. The faster rotational dynamics of NH 4 + in water is a central focus of these studies.…”

Structure and thermodynamics of H3O+(H2O)8 clusters: A combined molecular dynamics and quantum mechanics approach

“…In the case of H 3 O + (H 2 O) 8 , the box-like isomer A has the same oxygen framework as the lowest energy (H 2 O) 9 isomers -both have stacked water tetramers and pentamers. However, the (H 2 O) 9 structures have homodromic hydrogen bonding networks that are largely absent in the box-like isomers of H 3 O + (H 2 O) 8 8 with NH þ 4 ðH 2 OÞ 8 reveals significant spectral and structural similarities such as the presence of surface cations and box-like structures with one or two singly coordinated water molecules [7,93].…”

“…Improving our understanding of the configuration and thermodynamics of H 3 O + (H 2 O) 8 , or H + (H 2 O) 9 , clusters is an important step in elucidating how water molecules form larger clusters and, subsequently, aerosols in the atmosphere. This work is a continuation of long-standing efforts to explore ion-molecule interactions [4][5][6][7][8], hydrogen-bonded interactions [9][10][11][16][17][18][19][20][21][22][23][24][25][26][27][28], water cluster formation [3,4,[9][10][11][12][13][14][15][16][17][18][19][20], and atmospheric processes [5][6][7][8]12,[21][22][23][24][25][26]…”