Dual-cation ammine metal borohydrides are favorable hydrogen storage materials due to their high gravimetric density and relatively low hydrogen release temperature. By combining the Fast and Flexible CrystAl Structure Predictor with density functional theory calculations and Car-Parrinello molecular dynamics, we studied the polymorphism, the lattice stability, and the decomposition mechanism of LiMg(BH 4 ) 3 (NH 3 ) 2 in the temperature range 100−700 K. The onset of H 2 (g) formation is found at 400 K through the recombination of the hydrogen atoms from the bond cleavage of B−H and N−H in BH 4 and NH 3 groups. In addition to two hexagonal structures, of which one is the global minimum structure (P6 3 /m)) and the other corresponds to the experimentally proposed room-temperature structure (P6 3 ), a monoclinic (Cc) structure and two orthorhombic structures (Fmm2, Ima2) are proposed as stable structures.

Biomolecular self-assembly on surfaces is an emerging and exciting field for the fabrication of 2D nanostructures that are being used in a wide range of applications. Self-assembly of the nucleic acid bases, which are mostly stabilized by hydrogen bonding, in both solution and solid have been well characterized by various experimental techniques such as nuclear magnetic resonance (NMR) and scanning tunneling microscopy (STM). Especially for the surface based self assemblies, the resolution of STM images is quite insufficient to reveal the dominating intermolecular interactions which lead to the formation of self-assembled DNA bases. Moreover, it is also possible to form crystalline order self assemblies by finding suitable experimental conditions. This fact allows the application of crystal structure prediction (CSP) tools for the discovery of ordered self assemblies. In this regard, the existing CSP method called FFCASP has been extended with a new implementation allowing the prediction of 1D or 2D periodic and nonperiodic structures. The new approach, 2D-FFCASP, has been applied to four DNA bases and the best resulting structures have been further evaluated by dispersion-corrected density functional theory (DFT-D) and cluster in a molecule local correlation approach at the second-order Møller-Plesset perturbation (CIM-RI-MP2). 2D-FFCASP successfully reproduced the known self-assemblies of DNA bases in addition to many newly found isoenergetic structures.