# Low-temperature structures of C_{4} and C_{10} from the Car-Parrinello method: singlet states

## Abstract

We present the results of structural optimization and room-temperature molecular dynamics for the singlet states of C4 and C10, performed with the Car-Parrinello method. We show that density-functional theory in the local density approximation predicts the same equilibrium structures as first-principle (CI) calculations. Moreover, the study at T≈200-300 K reveals that C4 can be found in either the linear or nonlinear structure, while C10 is an interesting case of bistability, due to the dissymmetric nature of its ground state. The dynamical path in the oscillation between the two degenerate enantiomorphs is identified. At high temperatures both C4 and C10 are predicted to be linear. The transition path of the two aggregates from the cyclic structure to the chain is remarkably different. © 1990.