Empirical corrections in the G3X and G3X(CCSD) theories combined with a compact effective pseudopotential

Heats of formation for aluminium compounds with EnAt1 and EnAt2

“…This sequence of steps, along with the G3X and G3X(CCSD) methods and pseudopotential, generated EnAt1 "Festschrift in honor of Prof. Fernando R. Ornellas" Guest Edited by Adélia Justino Aguiar Aquino, Antonio Gustavo Sampaio de Oliveira Filho & Francisco Bolivar Correto Machado. [20] and EnAt2 [20], which provided results as accurate as the combination of G4CEP [18] and G3CEP [13] theories.…”

“…A recent endeavour to reduce the CPU time of calculations suggested the Gn theory started by Pereira et al [13,14], which associates a compact effective potential (CEP) [15] with the G3 theory, resulting in a method known as G3CEP [13,14]. After this first successful generalization by combining pseudopotential with the G3 theory, other proposals were expanded, such as G3(MP2)//B3LYP-CEP [16], G3(MP2)-CEP [17], G4-CEP [18], G3(MP2)// B3-SBK [19], G3X-CEP [20] and G3X(CCSD)-CEP [20]. Enforcement of these methods manifested a significant decrease in CPU time, preserving an outstanding accuracy when compared with the original all-electron versions.…”

“…Silva and Custodio [20] revealed the chance to improve the calculated enthalpies of formation with respect to accurate experimental data by scaling the atomization energies. This sequence of steps, along with the G3X and G3X(CCSD) methods and pseudopotential, generated EnAt1 "Festschrift in honor of Prof. Fernando R. Ornellas" Guest Edited by Adélia Justino Aguiar Aquino, Antonio Gustavo Sampaio de Oliveira Filho & Francisco Bolivar Correto Machado.…”

“…For 248 enthalpies of formation from the G3/05 test set, the MAE of the calculations with EnAt1 (1.02 kcal mol −1 ) and EnAt2 (0.98 kcal mol −1 ) is significantly better than the G3X-CEP results (1.16 kcal mol −1 ) and G3X(CCSD)-CEP (1.12 kcal mol −1 ) with the original experimental atomization energies. Silva and Custodio [20] calculated that Al 2 Cl 6 presented a MAE of 6.7 and 7.6 kcal mol −1 for G3X-CEP and G3X(CCSD)-CEP, respectively, whereas the MAE was 0.0 kcal mol −1 for both EnAt1 and EnAt2 methods.…”

Assessment of a composite method based on selected density functional theory methods and complete basis set extrapolation formulas

“…These experimental atomization energies present errors around 1%, with a maximum of 1.78% for Si, 1.28% for Al, and 1.57% for Be. In a recent paper, da Silva and Custodio suggested the possibility for improving the calculated enthalpies of formation with respect to accurate experimental data by scaling these atomization energies. This procedure, along with the G3X method and pseudopotential, provided results as accurate as the combination of the G4 theory with pseudopotential .…”