Improved modification for the density-functional theory calculation of thermodynamic properties for C–H–O composite compounds

Abstract

A three-parametric modification equation and the least-squares approach are adopted to calibrating hybrid density-functional theory energies of C(1)-C(10) straight-chain aldehydes, alcohols, and alkoxides to accurate enthalpies of formation DeltaH(f) and Gibbs free energies of formation DeltaG(f), respectively. All calculated energies of the C-H-O composite compounds were obtained based on B3LYP6-311++G(3df,2pd) single-point energies and the related thermal corrections of B3LYP6-31G(d,p) optimized geometries. This investigation revealed that all compounds had 0.05% average absolute relative error (ARE) for the atomization energies, with mean value of absolute error (MAE) of just 2.1 kJ/mol (0.5 kcal/mol) for the DeltaH(f) and 2.4 kJ/mol (0.6 kcal/mol) for the DeltaG(f) of formation.

Thermodynamic properties of formation estimated to biodiesel esters using Gaussian quantum chemistry software and group contribution method of Constantinou and Gani

“…With the data obtained from the elementary atoms and the molecules of interest, the atomization enthalpy and the atomization Gibbs free energy are calculated by Eqs. (1) and (2) [33]: The enthalpy of formation of the molecule can be written as a function of the enthalpy of atomization of the molecule and the enthalpies of formation of each atom that makes up the molecule, which can be seen in Eq. (3).…”

“…Thus, the insertion of three error correction parameters for the minimization of the error functions of Eqs. (5) and (6) was proposed [33]: Correction parameters were not entered in relation to the number of oxygen atoms since all the molecules studied have the same number of oxygens, which were 2 oxygens. Literature data of 26 molecules were used to determine the correction parameters.…”

“…Gaussian features a user-friendly computing environment and robust methods for a variety of calculations. There are several applications, such as characterization of chemical bonds [27][28][29], study of molecular vibrational dynamics [27], reactivity [29], potential redox [30], orbital optimization [31] and calculation of chemical properties [15,29,32,33].…”

“…The complement is "(d, p)", where "d" adds polarization functions on the main atoms and "p" adds functions in atoms of hydrogen [36]. The B3LYP/6-31G (d,p) model, wherein all the vibration frequencies are positive and minimum local energy are stable molecules, was already used and presented excellent results in other authors' works [15,33].…”

Theoretical modeling of the chemical synthesis and detonation performance of polynitrocubane derivatives

“…Adeyemo et al presented a hybrid support vector regression and gravitational search algorithm technique, which performed better than the methods described in previous older literature . Our lab created polyparametric least‐square modification equations to obtain an accurate gaseous molecular formation enthalpy . Whether obtained via experimental measurements or theoretical calculation, the molecular thermodynamic properties are of practical importance when performing a chemical study, in particular the parameter of enthalpy of formation, which can be used to estimate the explosion characteristics of an energetic material. where N , number of moles of gaseous products per gram of explosive; M , average molecular weight of gas products; Q , detonation heat; ρ , density of explosive.…”