Journal
ACS NANO
Volume 4, Issue 3, Pages 1703-1715Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn901592x
Keywords
quantum sieving; path integral Monte Carlo; hybrid Monte Carlo; grand canonical Monte Carlo; quantum rotors; isotopic effect; adsorption
Ask authors/readers for more resources
The effect of the quantized rotational degrees of freedom of hydrogen on the adsorption and sieving properties in carbon nanotubes is studied using computer simulations. We have developed a highly efficient multiple timestep algorithm for hybrid Monte Carlo sampling of quantized rotor configurations and extended the grand canonical Boltzmann bias method to rigid linear molecules. These new computational tools allow us to calculate accurately the quantum sieving selectivities for cases of extreme two-dimensional confinement as a function of pressure. The para-T(2)/para-H(2) selectivity at 20 K is analyzed as a function of the tube diameter and the density of adsorbed hydrogen. Extraordinarily high selectivities, up to 2.6 x 10(8), are observed in the narrowest nanotube. The quantized nature of the rotational degrees of freedom is found to dramatically affect adsorption and selectivity for hydrogen isotopes adsorbed in very narrow nanotubes. The T(2)/H(2) zero-pressure selectivity increases from 2.4 x 10(4) to 1.7 x 10(8) in the (3,6) nanotube at 20 K when quantum rotations are accounted for. The isotopic selectivity is found to increase with pressure, tending to a constant value at saturation. A simplified mean-field model is used to discuss the origin of this behavior.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available