Minimum-energy geometry

Silacyclopropane, 1,1 -difluorotetramethyl-decomposition, 1, 587 Silacyclopropanes, I, 575-581 ring expansion, I, 587 Silacyclopropenes, I, 583-587 minimum energy geometry, I, 587 ring expansion, 1, 587 7-Siladispiro[2.0.2.1 jheptane synthesis, I, 576... 

Cyclopentane is nonplanar, and the two minimum-energy geometries are the envelope and half-chair. In the envelope conformation, one carbon atom is displaced from the plane of the other four. In the half-chair conformation, three carbons are coplanar, vdth one of the remaining two being above the plane and the other below. The energy differences between the conformers are very small, and interconversion is rapid. All of the carbon atoms r idly move through planar and nonplanar positions. The process is called pseudorotation. 

The isomerization of alkenes is believed to take place via an excited state in which the two sp carbons are twisted 90° with respect to one another. This state is referred to as the p (perpendicular) state. This geometry is believed to be the minimum-energy geometry for both the singlet and triplet excited states. 

Weak interactions, such as van der Waals complexes or hydrogen bonds, are poorly predicted. Either the interaction is too weak, or the minimum energy geometry is wrong. 

Table 4.1 Minimum Energy Geometries for n Repelling Particles Constrained to Move on the Surface of a Sphere...

If the radical cation M2 (2 t y) is created according to equation 2 in its minimum-energy geometry when in the electronic state 2A>j, and if bothM(1 Po) and M 1 are in their... 

Figure 4. Minimum energy geometries of a generic bis-Cp olefin-free system.

Figure 5. Minimum energy geometry of the H2Si(Cp)2ZrC2H5+ species.

Figures. Minimum energy geometries of the H2Si(Cp)2ZrCH3(C2H4)+ system starting from the olefin-free H2Si(Cp)2ZrCH3+ species without, part a, and with, part b, a a-agostic interaction.

MO calculations are carried out for monomeric, dimeric and trimeric oligomers of PMMA. The minimum-energy geometry is achieved in all cases, and the geometrical and electronic parameters obtained are compared with experimental data. A tttg+ conformation along the main-chain skeletal sequence is found. 

Fig. 2.3 The H20 potential energy surface. The point Pmin corresponds to the minimum-energy geometry for the three atoms, i.e. to the equilibrium geometry of the water molecule...

Often the main result from a Hartree-Fock (i.e. an SCF) calculation is the energy of the molecule (the calculation of energy may be subsumed into a geometry optimization, which is really the task of finding the minimum-energy geometry). The STO-1G energy of HHe+ with an intemuclear distance of 0.800 A may be calculated from our results ... 

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