{'fraction_non_alphanumeric': 0.039423805913570885, 'fraction_numerical': 0.009097801364670205, 'mean_word_length': 5.700507614213198, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
First‐principles calculations on the origins of the gap bowing in BeSxSe1–x, BeSxTe1–x and BeSexTe1–x alloys

First‐principles calculations have been used to investigate the electronic structure and disorder effects in beryllium chalcogenides alloys (BeSxSe1–x, BeSxTe1–x and BeSexTe1–x) using the full potential‐linearized augmented‐plane wave method (FP‐LAPW) within density‐functional theory. We used the local‐density approximation within the generalized gradient correction as well as the Engel–Vosko GGA formalism to calculate the electronic structure at equilibrium volume. The ground‐state properties are determined for the bulk materials (BeS, BeSe, and BeTe) as well as for the average concentration (x = 0.5) of the alloys. Using the approach of Zunger and coworkers, the microscopic origins of compositional disorder have been detailed and explained. The disorder parameter (gap bowing) is found to be mainly caused by the chemical charge‐transfer effect, while the volume deformation and the structural relaxation contribute to the gap bowing parameter at smaller magnitude. This should be expected since there is a weak lattice mismatch between the binary compounds and a considerable electronegativity difference between Be and X (X = S, Se, Te) atoms. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)