Pulse-induced non-equilibrium dynamics of acetylene inside carbon nanotube: An ab initio study

Proceedings Of The National Academy Of Sciences Of The United States Of America 109, 8861 - 8865 (2012)

Pulse-induced non-equilibrium dynamics of acetylene inside carbon nanotube: An ab initio study

H. Zhang, Y. Miyamoto, A. Rubio

Nanoscale molecular confinement substantially modifies the func- tionality and electronic properties of encapsulated molecules. Many works have approached this problem from the perspective of quantifying ground-state molecular changes, but little is known about the nonequilibrium dynamics of encapsulated molecular sys- tem. In this letter, we report an analysis of the nonequilibrium dynamics of acetylene (C2 H2 ) inside a semiconducting carbon nano- tube (CNT). An ultrashort high-intense laser pulse (2 fs width and 10 15 W∕cm 2 intensity) brings the systems out of equilibrium. This process is modeled by comprehensive first-principles time-depen- dent density-functional simulations. When encapsulated, acetylene dimer, unlike a single acetylene molecule, exhibits correlated vibra- tional dynamics (C–C bond rotation and H–C–C bending) that is markedly different from the dynamics observed in the gas phase. This result highlights the role of CNT in modulating the optical elec- tric field within the tube. At longer simulation timescales (>20 fs) in the largest-diameter tube studied here [CNT(14,0)], we observe synchronized rotation about the C–C axes in the dimer and ulti- mately ejection of one of the four hydrogen atoms. Our results illustrate the richness of photochemical phenomena in confined geometries.

Additional Information

Download
Preprint - 729.47 KB
Doi
http://dx.doi.org/10.1073/pnas.1204388109

Related Research Areas