Revisiting the structure of (LiCH3)n aggregates using Car-Parrinello molecular dynamics

The theoretical study of (LiMe)(n) aggregates using Car-Parrinello molecular dynamics was undertaken. With respect to a quantum chemical static treatment, this approach furnishes supplementary information about the structural parameters. Equilibrium structures are indeed stable to ca. 300 K, provided the methyl groups in the aggregates are considered to rotate essentially freely. The Li-C distance depends on the coordination number of Li and not so much on the degree of aggregation. Finally, above 650 K, the cubic LiCH3 tetramer (which is energetically favored) undergoes an entropy-driven rearrangement to a planar structure.