Computational study of the solid-state vibrations and force field of magnesium and calcium hydroxides

Abstract

As vibrações no estado sólido dos hidróxidos de magnésio e cálcio foram estudadas através da análise de coordenadas normais. Usando um campo de força simples, de curto alcance, foram obtidas boas concordâncias entre as freqüências calculadas das vibrações normais e as fundamentais experimentalmente observadas. Algumas bandas fundamentais foram estimadas por meio de cálculos. Os cálculos de freqüência para os três modelos de cluster, através do método Hartree-Fock, indicam que o desdobramento dos estiramentos do grupo hidroxila pelo campo de correlação é principalmente originado em interações entre camadas.The solid-state vibrations of magnesium and calcium hydroxides have been studied by normal coordinate analysis. Using a simple short-range force field, the calculated frequencies of normal vibrations are in good agreement with the experimentally observed fundamentals. Some fundamental bands have been estimated by calculations. Hartree-Fock frequency calculations on three model clusters suggest that the correlation field splitting of the hydroxyl group stretching vibrations mainly originates in the interlayer interactions.

Raman and mid-infrared spectroscopic study of geometrically frustrated hydroxyl cobalt halides at room temperature

“…3, there are in fact two bands/peaks, although they are very near. According to Ergun et al [29] Lagaron, [30] and Hase, [31] one can safely assign the L-Cl IR bands 3566/3549 cm −1 , L-Br IR bands 3548/3524 cm −1 , L-Cl Raman peaks 3559/3546 cm −1 , L-Br Raman peaks 3540/3528 cm −1 , as the Davydov splittings of the hydroxyl stretching vibration mode ν(O-H), respectively.…”

Uranium (VI) Adsorbate Structures on Portlandite [Ca(OH)2] Type Surfaces Determined by Computational Modelling and X-ray Absorption Spectroscopy

“…Interactions of uranyl complexes with mineral surfaces: Uranyl has a propensity for uptake to a variety of common mineral surfaces, such as the carbonates including calcite or aragonite [7,8], silicates [9][10][11] and hydroxides such as brucite [12,13]. However, surprisingly, there has been relatively little research on the interactions of U(VI) with portlandite [Ca(OH) 2 ], with previous studies focussing on modelling [14][15][16][17] or determining its structural properties [18][19][20] and crystal morphology [5,6]. This is in large part due to the experimental difficulties associated with the high solubility and rapid dissolution kinetics of both CaO and Ca(OH) 2 .…”

Trimeric Hydrogen Bond in Geometrically Frustrated Hydroxyl Cobalt Halogenides

“…[26] However, the reason why the factor group splitting of OH group stretching vibration for Co 2 (OH) 3 Cl is smaller than the 62 cm −1 value for Co(OH) 2 can not be given by us now, and need be further studied by the quantum chemistry method. [27] Please note here that this Davydov splitting does not represent the existence of unequal O-H lengths.…”