The interaction energy between hydrocarbon chains

Abstract

A method is proposed for the determination of the interaction energy between isolated, parallel oriented, saturated, aliphatic hydrocarbon chains and the calculation is extended to include the monolayer case. The treatment is based upon the use of the second-order perturbation theory of quantum mechanics for the determination of the attractive (dispersion) component of the interaction potential. It is made applicable to long saturated hydrocarbon chains by utilizing the bond polarizability approximation method. The results compared favorably with those obtained by other investigators. An approximate form for the repulsive component of the interaction potential is provided. The total interaction potential obtained is approximately of the (5–11) form. The minimum energy position is calculated for the hydrocarbon chain crystal model allowing free rotation around the molecular axes by rotational averaging of the polarizability. The minimum energy position may occur at 5.0 Å interchain separation for the hexagonally packed hydrocarbon monolayer with 18 carbons per chain.