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美国政府科技报告
>Conformational Analysis of Poly-2,5-Benzimidazole (ABPBI), Poly-2,5-Benzoxazole (ABPBO), and Poly-2,6-Benzothiazole (ABPBT) Dimers by the Modified Neglect of Diatomic Overlap (MNDO) and Austin Method 1 (AM1) Semiempirical Molecula
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Conformational Analysis of Poly-2,5-Benzimidazole (ABPBI), Poly-2,5-Benzoxazole (ABPBO), and Poly-2,6-Benzothiazole (ABPBT) Dimers by the Modified Neglect of Diatomic Overlap (MNDO) and Austin Method 1 (AM1) Semiempirical Molecula
The two repeat unit analogs of three, aromatic, heterocyclic polymers were studied as part of the Materials Laboratory's research program to develop high-performance polymers with good environmental resistance. The Modified Neglect of Diatomic Overlap (MNDO) and Austin Method 1 (AM1) semiempirical orbital methods were used to calculate the change in of torsion angle versus heat of formation were obtained where minima on the curves represent the most thermodynamically stable conformations of the molecules. The AM1 method was found to be superior to the MNDO method in all cases. The MNDO method produced near perpendicular minima while AM1 gave planar or near planar minima, consistent with x-ray studies of the polymers. In all three cases the transoid conformations were lower in energy than the cisoid.
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