Structural, electronic, bonding, and elastic properties of NH₃BH₃: A density functional study

Abstract

The structural, electronic, bonding, and elastic properties of the low-temperature orthorhombic phase of NH(3)BH(3) are studied by means of first-principles total energy calculations based on the pseudopotential method. The calculated structural parameters of NH(3)BH(3) are found to be in good agreement with the experimental values. From the band structure calculations, the compound is found to be an indirect bandgap insulator with the bandgap of 5.65 eV (5.90 eV) with LDA(GGA) along the Γ-Z direction. The Mulliken bond population and the charge density distributions are used to analyze the chemical bonding in NH(3)BH(3) . The study reveals that B-H bonds are more covalent than N-H bonds. The elastic constants are predicted for ambient as well as pressures up to 6 GPa, from which theoretical values of all the related mechanical properties such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and anisotropy factors are calculated. It is found that NH(3)BH(3) is mechanically stable at ambient and also external pressures up to 6 GPa. As pressure increases all the calculated elastic moduli of NH(3)BH(3) increase, indicating that the compound becomes more stiffer and hard under pressure. From the ratio of shear modulus to bulk modulus (G/B), we conclude NH(3)BH(3) to be ductile in nature, and the ductility increases with pressure. The present results confirm the experimentally observed less plastic nature of the low-temperature phase of NH(3)BH(3) .

First-Principles Study on the Mechanisms for H2 Formation in Ammonia Borane at Ambient and High Pressure

“…Remarkably, the nonspherically nature of local electrons was also reproduced by the Born effective charge tensor. A recent ab initio study, however, reported a positively charged (and presumably “spherical”) H attached to boron site and a negatively charged H attached to nitrogen . This “peculiar” behavior might stem from the ill-defined Mulliken charge that has already been discussed in a review article and serves as additional support on the choice of the Born dynamical charge.…”

First-Principles Investigations of the Structure, Electronic, and Optical Properties of Mullite-Type Orthorhombic Bi2M4O9 (M = Al3+, Ga3+)

“…Population ionicities 0 and 1 correspond to the purely covalent and ionic bonds, respectively. 32 The calculated bond populations and their ionicity index of each M−O and Bi−O bond are reported in Tables 2 and 3. Mulliken bond population analysis and ionicity index values confirm that Bi−O bonds in both studied crystals have an ionic nature of more than 92%.…”

“…The population ionicity ( P i ) as a tangible function of the bonding nature can be estimated using the following equation: In the above equation P is the bond population for studied bond and P c is the bond population for a purely covalent bond, which is assumed to be equal to 1. Population ionicities 0 and 1 correspond to the purely covalent and ionic bonds, respectively . The calculated bond populations and their ionicity index of each M–O and Bi–O bond are reported in Tables and .…”

Prediction and characterization of a chalcogen–hydride interaction with metal hybrids as an electron donor in F2CS–HM and F2CSe–HM (M = Li, Na, BeH, MgH, MgCH3) complexes

“…[10][11][12][13][14][15] Hydrogen bonding has been acknowledged for a long time, but its classification becomes more rich depending on the electron donor, from lone pair electrons to p electrons in unsaturated compounds, s electrons in metal hydrides, single electrons in radicals, and carbenes. [16][17][18][19] Recently, people have diverted their attention to halogen bonding because this interaction has similar properties and applications to hydrogen bonding. [20][21][22] Correspondingly, different types of halogen bonds were also proposed, [23][24][25][26][27][28][29] being similar to the types of hydrogen bonding.…”