silicon for the chemical and solar industry XIII

Figure 1

: Diagram of possible skeletons of Si

molecule with 4 Si-Si bonds.

Structural optimization of the models

The all six models were found to have its equilibrium structure, which means that all

those stereoisomers theoretically exist. The all six models are stable or metastable in a

sense that they are located in the bottom of local potential well. The optimized

molecular structures of Model A ~ F are presented in Figures 2. The dashed lines in

the figure indicates the hydrogen bond.

The results of the MP2/6-31G* and RHF/6-31G* level calculations were compared and

the agreement between the both levels of calculations are satisfactory for the all models.

Therefore, the effect of electron correlation is not important as far as for the geometry

of the present models.

The data based on MP2/6-31G* level calculations were employed for the further study.

Figure 2

: Structures of six Si

molecule models with 4 Si-Si bonds optimized at MP2/6-

31G* level.

Figure 3 compares the total electronic energies plus nuclear repulsive energies, in other

words, the stabilities of the optimized Model A ~ F molecules. The condition at the

reference point for zero energy is that all component atoms are stationary or motionless

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