Theoretical investigation of the germanium arsenides

The ground state structures of the linear L-Ge-As and bent Ge-As-L systems (where L = H, Li, Na, BeH, MgH, BH2, AlH2, CH3, SiH3, NH2, PH2, OH, SH, F, Cl, and Br) have been investigated employing coupled cluster and density functional theory with the correlation consistent basis sets of double- through quadruple-ζ quality. The barriers to migration of the L group from the germanium terminus to the arsenic terminus have been determined by examining the transition state structure connecting the L-Ge-As and Ge-As-L minimum energy structures. Based on the computed transition states and classical barrier heights, new assignments in the relative stability of L-Ge-As compared with Ge-As-L, with respect to the L group, are proposed. The thermodynamic stability of these compounds is considered based on computed enthalpies of formation and enthalpies of isomerization. Relativistic effects are examined using two different approaches: the spin-free Cowan-Griffin and spin-free Douglas-Kroll-Hess Hamiltonians. Their impact on the atomization energies, enthalpies of formation, and enthalpies of isomerization upon germanium arsenide species is examined.