Hybrid covalent energy

A particularly important matrix element is that between hybrids pointed at each other, or into the bond, from two neighboring atoms. We call the magnitude of this matrix element the hybrid covalent energy,... 

For homopolar semiconductors, we see from Eq. (4-17) that it is twice the covalent energy -in contrast to the hybrid covalent energy of Eq. (3-6)- defined by... 

In the last step, we used Eq. (3-6) to write the hybrid covalent energy as... 

The meaning of 0, the angle of misalignment, is seen in Fig. 8-3. Expanding Eq. (8-7) for small 0 and small we obtain 0 = 2fi /3 the same result applies for every bond. We write the change in hybrid covalent energy, quadratic in 9, in the form... 

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