The ground state and polymorphism of LiSc(BH4)4 finally understood by Density Functional Theory modelling

TL;DR

This study uses Density Functional Theory to elucidate the polymorphism and ground state structure of LiSc(BH4)4, highlighting the significance of van der Waals interactions and revising previously reported phases.

Contribution

It introduces a new metastable gamma polymorph and clarifies the ground state structure of LiSc(BH4)4, incorporating dispersion corrections and revising existing phase descriptions.

Findings

Identification of a new gamma polymorph of LiSc(BH4)4

Revised understanding of the beta phase as a solid solution

Demonstration of van der Waals interactions' importance in modeling

Abstract

We report a new metastable gamma polymorph of mixed metal borohydride LiSc(BH4)4. Using Density Functional Theory calculations with dispersion corrections, we prove importance of van der Waals H...H interactions for correct theoretical description of the title compound. We propose the ordered ground state structure (alpha form) and revise the recently reported beta phase, now describing it as a solid solution, LiSc(BH4)4-xClx, x~0.7. The LiSc(BH4)4 polymorphism is rationalized using Zr(BH4)4 type structure with Sc --> Zr and Li in the interstitial face-centered positions.