Identifying Dirac cones in carbon allotropes with square symmetry

Jinying Wang1, Huaqing Huang, Wenhui Duan

  • 1College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.

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Adolf von Baeyer attempted to explain the instabilities of small and large cycloalkane rings using the concept of angle strain — the strain caused by the deviation of bond angles from the ideal 109.5° tetrahedral value for sp3  hybridized carbons. However, while cyclopropane and cyclobutane are strained, as expected from their highly compressed bond angles, cyclopentane is more strained than predicted, and cyclohexane is virtually strain-free. Hence, Baeyer’s theory that...
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