Electronic ground state of water

With six electrons from oxygen and two electrons from the hydrogens, the electronic ground state of water in this formulation is... 

Table 9 Force Constants for the Electronic Ground State of Water Obtained with the aug-cc-pVQZ Basis Set ...

The electronic ground state of the water molecule is Ai.83 In the region 1430-1860 A. (Fig. 18), there is a continuum whose maximum lies at about 1655 A. with / = 0.041.84 There appears to be some indication of weak bands. The second continuum, from 1250-1430 A., is clearly associated with superimposed diffuse bands and has / = 0.05. In both continua, predissociation is evident. Below 1250 A., a number of strong bands appear. In particular, the band at 1240 A. corresponding to the transition88 is of interest since some photochemistry has been done in this region. 

Processes (I) and (II) account for H20, whereas processes (I), (III), and (IV) describe the fate of e . According to Kaplan et al. [11], process (I) produces water molecules in high vibrational levels of their electronic ground state. The remaining H2O reacts with water to form H+q and OH in process (II). This ion-molecule reaction is known to occur in the gas phase with a rate constant of 8x10 dm mol sec [12], which, when extrapolated to liquid water, sets the lifetime of H20 in this medium at less than 10 " sec. However, Hamill [13] pointed out that H2O initially has the structure of a neutral water molecule so that it may migrate rapidly over distances of a few molecular diameters by resonant electron transfer with a succession of neighboring water molecules. 

Write down the electronic configurations for the ground states of the molecules water, carbon dioxide, formaldehyde, ethene, benzene, and the nitrogen dioxide radical. The occupied MO s shall be given using the full point group symmetry of the molecule. 

The material model consists of a large assembly of molecules, each well characterized and interacting according to the theory of noncovalent molecular interactions. Within this framework, no dissociation processes, such as those inherently present in water, nor other covalent processes are considered. This material model may be described at different mathematical levels. We start by considering a full quantum mechanical (QM) description in the Born-Oppenheimer approximation and limited to the electronic ground state. The Hamiltonian in the interaction form may be written as ... 

Figure 3.33 PE profiles of the electronic ground state (circles), the lowest 1 tttt state (squares) and the lowest 17rcr state (triangles) of (a) the phenol-water cluster and (b) the phenol-ammonia cluster as a function of the hydrogen transfer coordinate, calculated with the CASPT2 method [32].

The electron density was studied for the ground state of three groups of molecules (1) methane-methanol-carbon dioxide, (2) water-hydrogen peroxide, and (3) ferrous oxide-ferric oxide. 

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