In 1964 , Hückel method calculations ( using a simple linear combination of atomic orbitals ( LCAO ) method for the determination of electron energies of molecular orbitals of π electrons in conjugated hydrocarbon systems ) of molecules ranging in complexity from butadiene and benzene to ovalene , were generated on computers at Berkeley and Oxford .
In 1964 , Hückel method calculations ( using a simple linear combination of atomic orbitals ( LCAO ) method for the determination of electron energies of molecular orbitals of π electrons in conjugated hydrocarbon systems ) were generated on computers at Berkeley and Oxford .