Geometrical optimization

The investigation by Jorgensen and Lawesson (1985) supplements the foregoing discussion well. It is based on the concept of reactions controlled by charge and frontier orbitals (Klopman, 1974 Fleming, 1976). Geometrical optimization has been... 

The geometrically optimized model of BD had a roughly linear conformation. This spontaneous ordering was unexpected given the general orientation of dipolar molecules. Azobenzenes that have permanent dipoles parallel to the molecular axis would intuitively be expected to tend to pair with their dipole oriented in the opposite direction. The linear geometry is probably due to the... 

Fig. 5.16 Calculated structure of ferrous nitrosyl tetraphenylporphyrin Fe(TPP)(NO), resulting from geometric optimization with the B3LYP functional and 6-3IG -I- VTZ basis set [101]. Color scheme cyan = iron, green = carbon, blue = nitrogen, red = oxygen (taken from [101])...

Geometric Optimization. The structure of the molecule as built by CHEMLAB (or a input from other methods) can be optimized through either a full force field molecular mechanics calculation (MMII) or with the semi-empirical molecular orbital methods MINDO-3 and MNDO. 

The Gaussian 80 program l, as implemented on an IBM 370/3033 mainframe computer at the Notre Dame Computing Center, was used for most of the calculations. Calculations were also conducted with the Gaussian 86 program22a implemented on a Digital VaxStation 3200 computer. Geometric optimizations were performed with the minimal STO-3G basis set 3, 24 he split-valence... 

At the conclusion of a geometric optimization calculation, we have the equilibrium positions of all the atomic nuclei, as well as the overall electron density distributed in space (x, y, z). Many important properties, especially for an isolated single molecule at absolute zero temperature, can be obtained by solving the quantum mechanical or the molecular mechanical equations. Only the former method can produce electronic properties, such as electron distributions and dipole moments, but both methods can produce structural and energy properties. 

All geometrical optimizations were performed with the keywords tight and Int=UltraFine . The unsealed harmonic vibrational frequencies, zero-point vibrational energies (ZPVE), and enthalpies were also calculated. The ZPVE-corrected binding energies E , are reported throughout the work. 

---