Computer simulations of hydrocarbon chains with cis- double bonds: an investigation of intramolecular bond order characteristics

摘要

Computer simulations of isolated unperturbed hydrocarbon molecules of C{sub}18 with 1-5 methylene-interrupted cis double bonds have been carried out using Monte Carlo method based on the continuum model; the energy of nonbonded interactions, torsion and electrostatic terms have been taken into account. The molecule-fixed coordinate system (with the axes along principal axes of inertia of each molecule conformation) has been used. The orientation distribution functions ρ (θ) of C-H-bonds (θ is the angle between the bond and the axis), order parameters S relative to the maximum molecule span axis have been calculated. The widths of functions p (θ) (factor of bond "fluctuations") turned out to be dependent on the segment chemical structure and position; fluctuations increase from the centre of the chain towards the terminals, all things being equal. The orientation distributions p (θ) of C-H bonds flanking the double bond are the most narrow, the functions p (θ) of CH{sub}2-groups located between two double bonds are the most wide.