Calvo Florent
University of Grenoble Alpes, LIPHY, F-38000 Grenoble, France and.
CNRS, LIPHY, F-38000 Grenoble, France.
J Phys Chem A. 2015 Jun 11;119(23):5959-70. doi: 10.1021/jp510799h. Epub 2014 Dec 22.
The classical and quantum structures of cationic polycyclic aromatic hydrocarbon molecules (benzene, pyrene, coronene, and circumcoronene) coated by helium atoms have been theoretically investigated using a variety of computational methods. Classical shell filling, as determined from global optimization, is generally found to proceed by epitaxial additions on the graphitic surfaces before peripheral closure. From the quantum mechanical perspective provided by path-integral molecular dynamics simulations, vibrational delocalization is found to generally decrease the size of this first solvation shell, but also to give rise to a variety of situations in which the helium atoms are more or less localized depending on their environment, with strong finite size effects depending both on the hydrocarbon cation and the number of coating helium atoms. While the graphitic planes tend to bind helium sufficiently to give rise to snowball precursors, the peripheral regions are less dense and more delocalized, not as liquid as the outer layers but within an intermediate slushy character.
已使用多种计算方法对由氦原子包覆的阳离子多环芳烃分子（苯、芘、 coronene和circumcoronene）的经典和量子结构进行了理论研究。从全局优化确定的经典壳层填充通常发现是通过在石墨表面上外延添加，然后进行外围封闭。从路径积分分子动力学模拟提供的量子力学角度来看，振动离域通常会减小第一个溶剂化壳层的大小，但也会产生各种情况，其中氦原子根据其环境或多或少地局域化，存在强烈的有限尺寸效应，这既取决于烃阳离子，也取决于包覆氦原子的数量。虽然石墨平面倾向于充分结合氦以产生雪球前驱体，但外围区域密度较小且离域性更强，不像外层那样呈液态，而是具有中间的半液态特征。
