Estudo DFT das propriedades estruturais, eletrônicas e ópticas do cristal da L-histidina monoclínica

Abstract

In this work, we carried out a theoretical study of the monoclinic L-histidine crystal, which is one of the isomers of histidine (C6H9N3O2). Histidine is classified as an essential amino acid, with the presence of the imidazole ring in its constitution, whose structure has the capacity to act as a proton donor or proton acceptor or acting as a nucleophilic reagent. This amino acid plays a fundamental chemical and biological role in the structures and functions of proteins, in addition to participating in enzymatic catalysis reactions ie L-histidine as a free amino acid catalyzes and degrades various esters and has been applied in the reaction mechanism of a series of enzymes such as pancreatic ribonucleation, in addition to also participating in metal ion binders with copper, nickel, iron and zinc, and this amino acid is also involved in the production of red and white blood cells and is also present in the myelin of brain nerve cells . In particular, in this work, we are interested in possible applications in Nanoscience and Nanotechnology. Thus, we investigate structural, electronic and optical properties of the monoclinic L-histidine crystal by means of DFT formalism. For this, we use the GGA exchange and correlation function, in the parameterization of Perdew, Burke and Ernzerhof. Our calculations present a direct electronic main gap along the D → D direction of 4.38eV, which characterizes the investigated crystal as a wide gap semiconductor, we obtained a lower effective mass value for the electron and hole of 𝑚𝑒 = 3,44 𝑚0 and 𝑚ℎ = 3,06 𝑚0 along directions B → D and C → E, respectively.