| Summary: | 碩士 === 淡江大學 === 物理學系 === 88 === The element selenium exhibit highly anisotropic bonding under ambient conditions. The effect of pressure is to enhance the weak interchain bonding at the expense of the stronger intrachain covalent interactions. High-pressure experiments on selenium have been carried out and exotic high phases have been found：from a hexagonal to body-centered-cubic phase. Using density functional theory, we study the structural, vibrational and electronic properties of quasi-one-dimensional Se under hydrostatic pressure. Considering the anisotropic characteristic, we performed both local density approximation and general gradient correction for the exchange-correlation energy. To explore the complex compression mechanisms, we also calculation the pressure behavior of zone center phonons and elastic constants. Furthermore, we also study a possible pressure-induced lone-pair rearrangement by means of PDOS analysis.
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