Huckel MO Theory - Physical Chemistry - Lecture Notes, Study notes of Physical Chemistry

Download Huckel MO Theory - Physical Chemistry - Lecture Notes and more Study notes Physical Chemistry in PDF only on Docsity! Hückel MO Theory This is a primitive theory for systems with pi electrons. It treats only the pi electrons and ignores others. Example: Butadiene C 1 C 2 C 3 C 4 Definitions and Terminology: atomic orbital basis set consists of 4 pz orbitals is the self energy of an electron in one pz orbital is the H matrix element for adjacent pz orbitals. non-adjacent H matrix elements are zero overlap matrix elements zero, self overlap is one Therefore, the determinant looks like this: 0 00 0 0 00 E E E E Docsity.com To make it easier to solve, divide by and call x = -E: 0 100 110 011 001 x x x x Solve the quartic equation to find the four roots: x E +1.618 -1.618 +0.618 -0.618 -0.618 +0.618 -1.618 +1.618 Solve for the MO coefficients 0 0 0 0 43 432 321 21 xcc cxcc cxcc cxc Assign c2=1, then find the others: 2431 1111 x cx x c x c Docsity.com