Oxygen photoelectron spectrum of water clusters and free molecules (Ref. 15). Calibration of the ionization energy scale was based on an adiabatic ionization energy of free molecules, i.e., (Ref. 35). Courtesy of Gunnar Öhrwall.
(a) Correlation between full QM- and QM/MM-derived chemical shifts for a water cluster of size . A line of unit slope is included to guide the eye. (b) The chemical shifts from (a) convoluted with the lineshape of gas-phase water. The solid lines (circles) refer to the QM (QM/MM) model. The lineshape obtained using the QM/MM chemical shifts is shifted downward in energy by .
The distribution of O⋯O distances in a water cluster minimized using (a) AMOEBA and (b) CPMD. The shaded parts denote the distributions pertaining to tetrahedrally coordinated molecules.
Relative abundances of H-bonding patterns in a water cluster simulated using the AMOEBA force field.
The distribution of O⋯O distances in the first coordination shell of molecules making up the cluster, obtained from MD simulations using the AMOEBA force field. The solid, dashed, crossed, and dotted lines refer to , , , and structures, respectively.
The distribution of chemical shifts in ionization energy of molecules making up the bulk (dotted line) and surface (solid line) parts of the cluster, sampled over MD simulations using the AMOEBA force field. The shifts are computed using the QM/MM model.
Donor-acceptor internal shift in electrostatic potential at oxygen sites in a dimer of rigid water molecules given as a function of O⋯O distance.
(a) The distribution of O⋯O distances in the first coordination shell of molecules making up the cluster. (b) Chemical shifts in the ionization energy of the bulk molecules. The dotted and solid lines refer to AMOEBA and TIP5P structures, respectively.
Least-squares fits (thick solid lines) to the photoelectron spectrum (+) of water clusters based on theoretical models that pertain to (a) AMOEBA-based trajectory and (b) a combined model where the surface lineshape (dashed line) is taken from AMOEBA and the bulk lineshapes (dotted line) is taken from TIP5P.
(a) Average oxygen-oxygen distances and (b) binding energies of the dimer and cyclic oligomers up to the pentamer, as obtained from the force field (+) and ab initio (△) calculations.
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