tailieunhanh - Thermochemical parameters of some small pure and doped silicon clusters

Quantum chemical computations of thermochemical parameters of several series of small pure and doped silicon clusters are reviewed. We analyzed the performance of the coupledcluster theory with energies extrapolated up to complet basis set, CCSD(T)/CBS and the composite G4 method in determining the total atomization energies (TAE), standard heats of formation (∆fH 0 ), electron affinities (EA) and ionization energies (IE) and other thermochemical parameters with respect to available experimental data. The latter were determined with large error margins. | Vietnam Journal of Science and Technology 55 (6A) (2017) 18-34 THERMOCHEMICAL PARAMETERS OF SOME SMALL PURE AND DOPED SILICON CLUSTERS Nguyen Minh Tam1, 2, * 1 Computational Chemistry Research Group, Ton Duc Thang University, Ho Chi Minh City, Viet Nam 2 Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Viet Nam * Email: nguyenminhtam@ Received: 15 June 2017; Accepted for publication: 15 December 2017 ABSTRACT Quantum chemical computations of thermochemical parameters of several series of small pure and doped silicon clusters are reviewed. We analyzed the performance of the coupledcluster theory with energies extrapolated up to complet basis set, CCSD(T)/CBS and the composite G4 method in determining the total atomization energies (TAE), standard heats of formation (∆fH0), electron affinities (EA) and ionization energies (IE) and other thermochemical parameters with respect to available experimental data. The latter were determined with large error margins. Keywords: Silicon Clusters, Doped silicon clusters, Thermochemical parameters, Total atomization energies, Heats of formation, Ionization energies, electron affinities. 1. INTRODUCTION The heat of formation (or enthalpy of formation, denoted as ∆Hf, ∆fH, ∆fH0 ), which is a key and characteristic physico-chemical parameter of a molecular system, is of common use in many fields of chemistry. It is necessary for the evaluation of thermochemical quantities of a chemical system, or the energetic outcome of a chemical process. In the latter, knowledge of the heats of formation of the compounds involved is primordial in its thermodynamic and kinetic studies. The standard heat of formation of a substance X, determined at a reference pressure and at a given temperature, is the enthalpy of the reaction accompanying the formation of one mole of that substance from its constituent elements in their reference states. Reference states are defined as follows: i) for a gas: the standard .