First-Principles Design of a Deep-Ultraviolet Nonlinear-Optical Crystal from KBe2BO3F2 to NH4Be2BO3F2.

KBe2BO3F2 (KBBF) is so far the sole nonlinear-optical (NLO) material that can be practically applied in the deep-ultraviolet (DUV) region. For the purpose of overcoming its layering tendency in crystal growth, herein a computer-assisted material design system is employed to design a new KBBF analogue, ammonia beryllium fluoroborate (NH4Be2BO3F2, ABBF). The first-principles calculations demonstrate that ABBF possesses NLO properties very close to those of KBBF, thus exhibiting good DUV NLO capability. Moreover, owing to the relatively strong chemical binding between layers, ABBF would have a better growth habit compared with KBBF. Upon synthesis, ABBF would be a very promising DUV NLO material.