Under high pressure, a cagelike diamondoid nitrogen structure was lately discovered by first-principles structure researches. This newly proposed structure is very unique and has not been observed in any other element. Using density-functional calculations, we study the pressure effect on its vibrational properties. The Born effective charges are calculated, and the resulting LO-TO splittings of certain infrared active modes are beyond 20 cm 1 . We depict the Γ -point vibrational modes and find the breathing mode, rotational mode, and shearing mode. Frequencies of all the optical modes increase with pressure increasing. Moreover, the relation between the breathing mode frequency and the nitrogen cage diameter is discussed in detail. Our calculation results give a deeper insight into the vibrational properties of the cagelike diamondoid nitrogen.
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机译：Atmospheric Pressure of Nitrogen Plasmas in a Ferro-electric Packed-bed Barrier Discharge Reactor Part II: Spectroscopic Measurements of Excited Nitrogen Molecule Density and its Vibrational Temperature
机译：Studies from Center for High Pressure Science and Technology Advanced Research (HPSTAR) Have Provided New Data on Mineral Research (Phase Stability and Vibrational Properties of Iron-Bearing Carbonates at High Pressure)
