Question

The Hückel approximation may also be used to predict the atomic orbital co- efficients associated with each molecular orbital. a) Evaluate the matrix product HV = EV for the ground state of a Hückel di- atomic (such as H2 or ethene), to show that the two atomic orbital coefficients must be equal, ca = cb = c. b) Determine the value of c by using the fact that normalization requires that c. +c =1.

Answer 1

The secular eqh are G(2-6) + C, B 0 - 1 GB + 22 (2 t) = 0 till Taking ß common from (1) 2 (ii) All4(**) +-)) = 0 P(( 4+6 (24) = 0 ante o citano For bonding liver (>=-1) - City o ام ع normalization condition chc=1 41-42 4, H(Pi+) - For bonding 4,- *(RR) - For antibonding