The shape of unperturbed polymer chains was studied using the Monte Carlo technique on a tetrahedral lattice.The asphericity A

the ratios/and/ were calculated for different values of polymer chain length n

conformational energy ε (ε≥0) and temperature T. The asphericity A decreases with the increase of chain length and tends toreach its limiting value rapidly with the decrease of γ(γ=ε/kBT). For large n

A is about 0.525±0.005

the ratios22/12and 32>/L12 are about 2.7 and 12.0

respectively

and are almost independent of γ

but for short chains

they depend on γ.