Electronic structure calculations and molecular dynamics simulations of hydrogen adsorption on Beryllium doped complexes

Interaction of molecular hydrogen with Be and Be2 decorated acetylene is studied using first principles calculations and molecular dynamics simulations. C2H2Be and C2H2Be2 complex can interact with maximum of two and four H2 molecules respectively thereby showing respective H2 uptake capacity of 10.3 and 15.5 wt % and is well above the target set by U.S. department of energy. Temperature dependent Gibbs free energy corrected adsorption energy shows that H2 adsorption on C2H2Be is energetically favorable below 250 and 200 K and 1 atm. pressure at MP2/6-311++G** and CCSD(T)/6-311++G** level whereas it is energetically favorable on C2H2Be2 at entire temperature and pressure range considered here from 50 K to 400 K and 50 atm to 400 atm. The desorption temperature obtained for C2H2Be(2H2) and C2H2Be2(4H2) complexes at MP2/6-311++G** level using van't Hoff equation is 281 and 638 K respectively. Molecular dynamics simulations performed at different temperature show that all the adsorbed H2 molecules remain adsorbed during the simulations on a complex at temperature T only if Gibbs free energy corrected H2 adsorption energy at that temperature T is positive. H2 adsorption on Be decorated ethylene is also studied and the results are compared with Be decorated acetylene.