Theabinitiocrystal orbital method has been applied to study the electronic ground state of an infinite polyethylene chain in the allhyphen;transconformation within the framework of the Hartreendash;Fock approximation. Gaussian basis sets of minimal and double zeta quality have been used to evaluate equilibrium geometry and longitudinal elastic modulus of this model system. A structure withrCC= 2.952 bohr,rCH= 2.082 bohr, arcl;CCC = 112.2deg;, and arcl;HCH = 107.4deg; has been found to be most stable and a longitudinal elastic modulus of 345 GPa is predicted. Basis set dependence and the influence of lattice sum truncations on the electronic band structure are thoroughly discussed. Calculations including polarization functions have subsequently been performed in order to obtain electronic band structure and density of states at a near Hartreendash;Fock limit quality.
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