This article is cited in
5 papers
Thermophysical Properties of Materials
Anharmonicity in the $\mathrm{V_2O_3}$ molecule and thermodynamic properties of $\mathrm{V_2O_3}$ in the gas phase
A. V. Gusarov,
E. L. Osina Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya ul. 13, Bd. 2, Moscow, 125412, Russia
Abstract:
A quantum-mechanical calculation of the relative stability, structural parameters, and vibrational frequencies of
$\mathrm{V_2O_3}$ molecule isomers for different spin states was carried out using the
$\text{BPW91/6-311}+G(d, p)$ method. It was shown that the isomer with the
$C_s$ structure (nonplanar VOVO rectangle with an O atom attached to it) in the
$X^5A''$ electronic state possesses the maximum stability. The energy of the
$C_{2v}$ symmetry structure was higher than the lowest energy by just
$23 \text{ cm}^{-1}$. It definitely indicated the impossibility of usage of the harmonic model in order to calculate the thermodynamic functions of
$\mathrm{V_2O_3}(g)$. A model is proposed based on which the energy levels and vibrational sums of states for this type of motion were calculated for the
$C_s\to C_{2v}\to C_s$ transition coordinate. These data, as well as results obtained from quantum-mechanical calculations, were used to calculate the thermodynamic functions of
$\mathrm{V_2O_3}(g)$ in the temperature range of
$T=100$–
$6000$ K. The calculations were performed with the five excited electronic states with energies from
$1000$ to
$9000\text{ cm}^{-1}$ taken into account. A comparison with the data calculated in the “rigid rotator-harmonic oscillator” approximation was performed.
UDC:
536.7+541.11
Received: 20.12.2010