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Prediction of the Condensed Phase Enthalpy of Formation of Nitroaromatic Compounds Using the Estimated Gas Phase Enthalpies of Formation by the PM3 and B3LYP Methods

Oftadeh M., Keshavarz M. H., Khodadadi R.

Central European Journal of Energetic Materials

2014

Vol. 11, no. 1

143--156

A new method is introduced to correlate the condensed phase enthalpies of formation of nitroaromatic compounds with their gas phase enthalpies of formation on the basis of the B3LYP/6-31G* and PM3 methods. For the B3LYP method, the condensed phase enthalpy of formation depends on the number of certain elements, nitro groups and aromatic rings. For the PM3 method the number of N=N or N≡N groups, and the presence or absence of three interconnected rings, in addition to some of the parameters mentioned above, are necessary in order to obtain a reliable correlation. For 72 nitroaromatic compounds, the calculated root mean square (rms) deviations of the condensed phase enthalpies of formation of nitroaromatic compounds using the B3LYP and PM3 methods are 63.63 and 32.17 kJ/mol, respectively. The results predicted on the basis of the PM3 method are compared with the best available experimental data.

Determination of the electronic band structure of the rutile polymorph of TiO2: a quantum chemical approach

Bardziński P. J.

Materials Science Poland

2011

Vol. 29, No. 3

223--232

The aim of this work is the investigation of the relationship between the electronic band structure of the TiO2 rutile and the dimensionality of the system. For three dimensional system the bulk form of rutile was considered, while a slab model was chosen in order to represent the titanium (IV) dioxide (110) surface. The influence of changing the number of atomic layers on the bandgap value for the (110) surface was also examined. Density of states referring to the bands from the first valence band up to the bottom of the conduction band was projected on the whole set of atomic orbitals as well as on the significant shells of the titanium and oxygen atoms. Ab initio calculations with a B3LYP functional were carried out. Basis sets used were modified Ti 86-411(d31)G darco unpub and O 8-411 muscat 1999. The results are compared with experimental and computational data already available in the literature. Surface termination problem was discussed and the application of the obtained results as a starting point to obtain the first model of the rutile titania nanotube was proposed. The surface formation energies for rutile planes with a different surface terminations were compared and the modification to the equation needed for surface energy calculation was introduced.