Crystal structure of α‐gutta percha: Modification of the constrained least‐squares method

The crystal structure of α‐gutta percha has been determined by x‐ray diffraction. The unit cell parameters are a = 7.98 Å, b = 6.29 Å, c (fiber period) = 8.77 Å, and β = 102.0° (monoclinic). The space group is P 2 1 / c – C 2 h 5 . Two molecular chains of nearly trans‐CTS‐trans‐CTS̄ conformation pass through a unit cell; C , T , S , and S̄ being the cis , trans , and two types of skew forms, respectively. The constrainedle astsquares method was modified so that the order of the least squares matrix could be reduced and was applied to the refinement of the crystal structure.