Lithium dihydroborate: first-principles structure prediction of LiBH2.

Area of Science:

• Solid-state chemistry
• Computational materials science
• Crystallography

Background:

• Lithium borohydrides are promising hydrogen storage materials.
• Understanding their crystalline structures is crucial for material design.
• First-principles structure prediction offers a powerful tool for exploring novel materials.

Purpose of the Study:

• To predict the stable crystalline structures of LiBH(2) using computational methods.
• To determine the ground state structure and relative stability of various LiBH(2) polymorphs.
• To provide simulated diffraction and spectroscopic data for potential experimental validation.

Main Methods:

• First-principles structure prediction employing simulated annealing and density functional theory.
• Modeling unit cells with four formula units and without symmetry restrictions.
• Calculation of formation enthalpies at 0 Kelvin.

Main Results:

• The predicted lowest energy structure features linear anionic chains, (∞)(1)[BH(2)], with a formation enthalpy of -90.07 kJ/mol.
• Stable ring structures with butterfly and planar square topologies were identified, but are energetically less favorable.
• Convergent structures were found within monoclinic, tetragonal, and orthorhombic symmetry families.

Conclusions:

• The ground state of LiBH(2) is characterized by linear [BH(2)] anionic chains.
• Simulated X-ray diffraction patterns and infrared spectra are provided for identified structures.
• This work provides fundamental insights into the structural landscape of LiBH(2).