Vibrational spectrum of brucite, Mg(OH)2: a periodic ab initio quantum mechanical calculation including OH anharmonicity

摘要: Abstract The harmonic frequency spectrum of bulk Mg(OH)2, brucite, has been computed with the CRYSTAL periodic code, using four different hamiltonians, namely Hartree–Fock (HF), local density (LDA), gradient corrected PW91 and hybrid B3LYP. anharmonicity OH stretching also evaluated, as well transverse/longitudinal optical (TO/LO) splitting. Comparison frequencies single layer shows that splitting is due to interlayer interaction. Agreement experiment excellent for B3LYP (less than 10 cm−1 differences), less so much satisfactory both LDA HF.