The first-principle studies of the elastic, electronic, and vibrational properties of L-alanine

Autor: Tigran L. Prazyan, Yurii N. Zhuravlev
Rok vydání: 2019
Předmět:
Zdroj: Structural Chemistry. 30:1243-1255
ISSN: 1572-9001
1040-0400
DOI: 10.1007/s11224-019-1277-7
Popis: The calculation in the present work is conducted with the help of CRYSTAL’17 package using PBE method, including gradient approximation and taking into account van der Waals forces as well as the B3LYP hybrid functional. Crystal structure and chemical bond, elastic properties, equation of state, structural properties under pressure, and vibrational properties are studied. The elastic constants of single crystal and polycrystalline properties are obtained; anisotropic nature of the crystal is determined. The impact of hydrostatic compression up to pressure of 7.5 GPa on the L-alanine properties is studied. The effect of taking into account the forces of intermolecular interaction on the accuracy of calculation of lattice constants and intermolecular distances is shown. The atom charges and bond overlap population in molecules are determined within the framework of the Mulliken scheme. The total and partial density of states is calculated and it is established that the transition from valence band to conduction band is performed by electrons from oxygen atoms to carbon atoms of the –COO group. The average value of the tensor component of the polarizability, permittivity, and piezoelectric stress coefficients were 40.67 A3, 2.08, and − 4.25 pm/V, relatively. The obtained dependence of the lattice constants demonstrated occurrence of intersection within pressure interval of about 1.8 GPa, the fact that has earlier been established experimentally. It has been shown that C–C and C–N intramolecular distances reduce with pressure increase, as for the –COO group, C1–O1 distances decrease, while C1–O2 distances increase. The mode Gruneisen parameters, obtained from ab initio calculations for the first time, revealed the increase in the vibration frequency of the –NH3 group, while other vibration frequencies decrease with increasing pressure.
Databáze: OpenAIRE
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