C_(60)、C_(240)、C_(60)@C_(240)富勒烯分子压缩特性的分子动力学研究

Compressive mechanical properties of C_(60),C_(240) and C_(60)@C_(240) fullerenes

采用Tersoff-Brenner势的分子动力学方法,研究了双石墨层作用下C60、C240及C60@C240富勒烯分子的压缩力学特性.根据计算结果,讨论了三种分子压缩过程中几何构形、能量、压缩载荷等的变化及其差异.研究表明,压缩过程中,仅C240分子出现了“塌陷”现象,塌陷时,该分子的能量及外载一度下降;相同压缩应变下,C240的体积压缩率以及C60@C240的能量吸收率最大,而C60的体积压缩率及能量吸收率均最小;C60@C240分子的最大承载能力及C240的最大承受变形能力最大,而C60分子的最大承载和最大承受变形能力均最小;在C60@C240分子的压缩中,当应变小于20%时,内笼C60的体积及其能量变化很小;C60与C240之间的范德华尔能在整个压缩C60@C240分子的能量变化中仅仅占有非常小的份额.

By the Tersoff-Brenner potential based MD(Molecular dynamics) method,the compressive properties of C_(60),C_(240) and C_(60)@C_(240) fullerenes under the action of double graphite layers were investigated.According to the obtained results,the variations and differences of geometrical configurations,energy and external loading for the three molecules during the compressions were discussed.It is shown that,① during the compression,the 'cave-in' phenomenon only occurs to the C_(240) molecule,and,at the time of 'cave-in',the energy and external loading for the C_(240) fall;② for the same compressive strain,C_(240) has the maximal volume-shrinkage,C_(60)@C_(240) has the maximal energy-absorb capability,and C_(60) has the minimal volume-shrinkage and energy-absorb capability;③ C_(60)@C_(240) molecule has the maximal load-support capability,C_(240) has the maximal deformation-support capability,and C_(60) has the minimal load-support and deformation-support capability;④ the volume and energy of the inner cage C_(60) in the compressed C_(60)@C_(240) molecule varies slight when strain is less than 20%,and the Van der Waals energy between C_(60) and C_(240) is slight during the whole compression.