The equilibrium geometry of the water dimer computed at the level. The configuration is of symmetry. Due to the formation of the H bond, the bond is slightly elongated at compared to for and for and . The H bond is nearly collinear (angle ) with a H-bond length of .
The HOMO of the water dimer. Shown is the domain where the density of the orbital is high. The two different shadings indicate two opposite signs of the wave function.
The high density domains, for electrons of spin , of the HOMO (top) and the LUMO (bottom) of the cation water dimer at the geometry of the neutral dimer as shown in Fig. 1. The energies are (LUMO, MO ) and (HOMO, MO ). Compare with Fig. 2 that shows the HOMO of the neutral that is localized on the water molecule on the left.
The weights of the HOMO of the neutral water dimer expanded in the orbitals of the cation plotted against the orbital energies. Since the HOMO of the neutral is orbital number 10 the naive expectation is that only orbital 10 of the cation contributes. This is partly but not completely the case. Orbital 9 of the cation also contributes in a significant fashion. This can also be seen from Fig. 2 and 3 above taking advantage of the shading that indicates the phase of the wave function.
The dephasing of a hole created by suddenly removing an electron from the HOMO of the water dimer. Shown is the population of the positive charge (left) and the water molecules (right) (see Fig. 1). The temporal evolution is primarily an oscillation between the LUMO and HOMO of the cation.
The mdw (top) and wdm (bottom) conformers of the water-methanol bimer. The computed bond lengths and angles are in agreement with literature values (Refs. 38–40). The axes are shown for the mdw bimer because as discussed in Sec. V, the response of the molecule depends on the orientation of any applied field and the field in Fig. 13 below is applied in either the positive or negative direction.
Dephasing of the initially localized hole in the neutral of the water-methanol bimer. For this conformer the cation has delocalized LUMO and HOMO orbitals. The computation for the MOs of the cation are carried out at the unrestricted level.
Equilibrium geometry of the weakly bound NO dimer as computed at the B3LYP level of theory. The N–N bond length is , the NNO angle equals 101.4°, and the NO bond length is .
HOMO of the weakly bound NO dimer.
Energies of the MOs of the NO dimer (MO 7–MO 20, HOMO is MO 15) vs the strength of the electric field applied along the N–N bond in a.u. To convert to the voltage applied on the N–N bond, note that and the computed N–N bond length is .
Field distorted HOMO of the NO neutral dimer for electric field strengths applied in the N–N direction as indicated.
Fast electronic reorganization in the NO dimer when the ionization includes the effect of charge distortion by a static electric field of Initially, the hole density is predominantly localized on the right NO molecule ( in Fig. 8 above).
Time evolution of a hole created in the HOMO of the neutral in the presence of an external uniform electric field of oriented along the direction. See Fig. 6 for the definition of . Full line: methanol: dotted line: water: full squares: : full circles: .
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