Ab initio calculation of polyethylene deformation including electron correlation effects

The longitudinal acoustic elastic modulus of polyethylene has been calculated with the aid of the ab initio crystal orbital method applying corrections also for electronic correlation effects. The basis set and correlation dependence of the elastic modulus have been investigated. The best theoretical value of 305 GPa of this modulus is in reasonable agreement with the published experimental values. At an elongation of ca. 0.1 the deviation from Hooke's law is found to be substantial.