Discovering Amorphous Indium Phosphide Nanostructures with High-Temperature ab Initio Molecular Dynamics

We employ high-temperature ab initio molecular dynamics (AIMD) as a sampling approach to discover low-energy, semiconducting, indium phosphide nanostructures. Starting from under-coordinated models of InP (e.g. a single layer of InP(111)), rapid rearrangement into a stabilized, higher-coordinate but amorphous cluster is observed across the size range considered (In[subscript 3]P[subscript 3] to In[subscript 22]P[subscript 22]). These clusters exhibit exponential decrease in energy per atom with system size as effective coordination increases, which we define through distance-cutoff coordination number assignment and partial charge analysis. The sampling approach is robust to initial configuration choice as consistent results are obtained when alternative crystal models or computationally efficient generation of structures from sequential addition and removal of atoms are employed. This consistency is observed across the 66 structures compared here, and even when as many as five approaches are compared, the average difference in energy per pair of atoms in these structures is only 1.5 kcal/mol at a given system size. Interestingly, the energies of these amorphous clusters are lower than geometry optimized spherical models of bulk InP typically used for simulations of quantum dots. Favorable energetics appear correlated to highlycoordinated indium and phosphorus with coordination numbers up to five and seven, respectively, as well as formation of phosphorus-phosphorus bonds.National Science Foundation (U.S.) (Grant ECCS-1449291

Search for the global minimum structures of AlB3H2n (n=0-6) clusters

The global minimum structures of AlB3H2n (n = 0–6) clusters are determined using the stochastic search method at the B3LYP/6–31G level of theory. These initially specified geometries are recalculated using B3LYP and CCSD(T) methods using the 6–311++G** basis set. The structural and electronic properties of the two lowest-lying isomers are presented. The structural parameters obtained for aluminum borohydride are compared with the experimental and theoretical results. The H2 fragmentation energies of the most stable isomers are investigated. Chemical bonding analyses for the global minimum of AlB3H2n (n = 0–6) clusters are performed using the adaptive natural density partitioning method

Search for the Global Minimum Structures of AlB3H2n (n=0-6) Clusters

The global minimum structures of AlB3H2n (n=0-6) clusters are determined using the stochastic search method at the B3LYP/6-31G level of theory. These initially specified geometries are recalculated using B3LYP and CCSD(T) methods using the 6-311++G(**) basis set. The structural and electronic properties of the two lowest-lying isomers are presented. The structural parameters obtained for aluminum borohydride are compared with the experimental and theoretical results. The H-2 fragmentation energies of the most stable isomers are investigated. Chemical bonding analyses for the global minimum of AlB3H2n (n=0-6) clusters are performed using the adaptive natural density partitioning method.&nbsp;</p