Vertical ionisation potentials

The lowest electronic states of Bz+ are of the following symmetry species (at the D6h nuclear configuration, vertical ionisation potentials (IPs) from Ref. [23] given in parentheses) ... 

Table 1. Ab initio calculated coupling constants, frequencies and vertical ionisation potentials (IPs) for the coupled X — B states of Bz+ frequencies are from an MP2 force field calculation for the neutral ground state, coupling constants and IPs from ab initio Green s function results...

Table 1. Vertical ionisation potentials and nj -> n transition energies (eV) of diazenes1)...

Table 6. Comparison between measured vertical ionisation potentials/v,j and calculated orbital energies of trithiapentalene and analogous compounds. The calculations have been carried out on the unsubstituted compounds except for the ab initio calculation on IVh. All values in eV...

The greatest improvement of the DFT-SAPT method over the original SAPT is the acceleration of the calculations by one order of magnitude. The intramolecular treatment is conducted using the DPT and therefore suffers from inaccurate energies of the virtual orbitals. This drawback is corrected for in advance of the actual SAPT treatment by a gradient-controlled shift procedure, which uses the difference between the exact vertical ionisation potential (IP) and the energy of the (HOMO) [24]. In this work, PBEO/aug-cc-pVTZ and PBEO/aug-cc-pVDZ calculations were carried out to obtain the IP respective HOMO values and intermolecular terms were described by aug-cc-pVDZ and aug-cc-pVTZ basis sets. Bromine and iodine atoms were treated by pseudopotentials to describe relativistic effects of inner-core electrons correctly. 

Fig. 12. Vertical ionisation energies, Fermi (E.) and vacuum levels (V. L.) for gaseous (1), condensed and chemisorbed phases of (a) benzene, (b) acetylene and (c) ethylene, all plotted relative to cr-orbital ionisation potentials (I. P.) for the gas phase. Relaxation shifts are given by the vacuum level shifts while bonding shifts are given by relevant jr-orbital shifts. [Reproduced with permission from J. E. Demuth and D. E. Eastman, Phys. Rev. Letters 32, 1123 (1974)]...

IE,IP) ionisation potential. Compare with adiabatic ionisation energy, vertical ionisation energy, electronegativity, and electron affinity. The energy needed to remove an electron from a gaseous atom or ion. 

Figure 1.3. Real-time femtosecond spectroscopy of molecules can be described in terms of optical transitions excited by ultrafast laser pulses between potential energy curves which indicate how different energy states of a molecule vary with interatomic distances. The example shown here is for the dissociation of iodine bromide (IBr). An initial pump laser excites a vertical transition from the potential curve of the lowest (ground) electronic state Vg to an excited state Vj. The fragmentation of IBr to form I + Br is described by quantum theory in terms of a wavepacket which either oscillates between the extremes of or crosses over onto the steeply repulsive potential V[ leading to dissociation, as indicated by the two arrows. These motions are monitored in the time domain by simultaneous absorption of two probe-pulse photons which, in this case, ionise the dissociating molecule.

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