182 research outputs found

    Electron Collisions with CO Molecule: An R-Matrix Study Using a Large Basis Set

    Get PDF
    Fixed-nuclei R -matrix calculations are performed at the equilibrium geometry of carbon monoxide using the very large cc-pV6Z Gaussian basis set. Results from a close-coupling model involving 27 low-lying target states indicate the presence of three2Σ+ resonances at 10.1 eV (width 0.1 eV), 10.38 eV (0.0005 eV), and 11.15 eV (0.005 eV), a2Δ resonance at 13.3 eV (0.1 eV) and two2Π resonances at 1.9 eV (1.3 eV) and 12.8 eV (0.1 eV). These new results are in very good agreement with many experimental studies but in contrast to a previous calculation using a smaller cc-pVTZ basis set where we found only one2Σ+ resonances at 12.9 eV. This is the first time that any theoretical study has reported these high lying2Σ+ resonances in agreement to experiment and reported detection of a2Δ resonance. Total, elastic and electronic excitation cross sections of CO by electron impact are also presented

    Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose IÎČ

    Get PDF
    Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (Molecular Mechanics) have been performed to investigate the mechanism for auxetic (negative Poisson’s ratio) response in crystalline cellulose IÎČ from kraft cooked Norway spruce. An initial investigation to identify an appropriate force field led to a study of the structure and elastic constants from models employing the CVFF force field. Negative values of on-axis Poisson’s ratios nu31 and nu13 in the x1-x3 plane containing the chain direction (x3) were realized in energy minimizations employing a stress perpendicular to the hydrogen-bonded cellobiose sheets to simulate swelling in this direction due to the kraft cooking process. Energy minimizations of structural evolution due to stretching along the x3 chain direction of the ‘swollen’ (kraft cooked) model identified chain rotation about the chain axis combined with inextensible secondary bonds as the most likely mechanism for auxetic response

    The hygroscopic power of amorphous cellulose: A modeling study

    No full text
    International audienc

    On the external morphology of native cellulose microfibrils

    No full text
    International audienc
    • 

    corecore