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Title: Coupled Cluster Theory Determination of the Heats of Formation of Combustion-related compounds: CO, HCO, CO2, HCO2, HOCO, HC(O)OH and HC(O)OOH

Abstract

Coupled cluster theory through quasiperturbative, connected triple excitations (CCSD(T)) was used to obtain optimized structures, harmonic vibrational frequencies and heats of formation for seven related small molecules. For the three systems possessing reliable experimental heats of formation, the level of agreement between theory and experiment was excellent. In order to achieve this level of agreement and to simultaneously minimize the theoretical uncertainty it was necessary to apply large correlation consistent basis sets (through septuple zeta in some cases) followed by a number of small, but nonnegligible, energetic corrections. For CO, {Delta}H{sub f}{sup 0}(0 K) = -27.0 {+-} 0.2 (theory) vs -27.20 {+-} 0.04 kcal/mol (expt.). For CO{sub 2}, {Delta}H{sub f}{sup 0}(0 K) = -93.7 {+-} 0.2 (theory) vs -93.97 {+-} 0.01 kcal/mol (expt.). For HC(O)OH (formic acid), {Delta}H{sub f}{sup 0}(0 K) = -88.9 {+-} 0.4 (theory) vs -88.7 {+-} 0.1 kcal/mol (expt.). For HCO, the experimental and theoretical values are in near perfect agreement, with {Delta}H{sub f}{sup 0}(0 K = 10.4 {+-} 0.2 (theory) vs 10.3 {+-} 2 kcal/mol (expt.)), although this may be somewhat fortuitous since the experimental value is not very reliable. For trans-HOCO, we predict a value of {Delta}H{sub f}{sup 0}(0 K = -43.9 {+-} 0.5), comparedmore » to the revised photoionization value of {ge}45.8 {+-} 0.7 kcal/mol. Theory, however, is in good agreement with the possible experimental value of -42.7 {+-} 0.9 kcal/mol suggested in the same photoionization experimental analysis. For HCO{sub 2} and HC(O)OOH, where no experimental data exists, {Delta}H{sub f}{sup 0}(0 K = -27.6 {+-} 0.4 and -65.6 {+-} 0.6 kcal/mol respectively). trans-HOCO is only slightly bound (1.1 kcal/mol) with respect to the H + CO{sub 2} asymptote. HCO{sub 2} is 15.7 kcal/mol higher in energy than trans-HOCO and lies above the H + CO{sub 2} asymptote by 14.6 kcal/mol. It is only bound with respect to the OH + CO asymptote by 9.0 kcal/mol. Three parameterized methods (G2, G3 and CBS-Q) were compared to the best coupled cluster heats of formation and found to differ by up to 3.2 kcal/mol.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
15010162
Report Number(s):
PNNL-SA-36713
KC0301020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A, 107(10):1604-1617
Additional Journal Information:
Journal Name: Journal of Physical Chemistry A, 107(10):1604-1617
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY

Citation Formats

Feller, David F, Dixon, David A, and Francisco, Joseph. Coupled Cluster Theory Determination of the Heats of Formation of Combustion-related compounds: CO, HCO, CO2, HCO2, HOCO, HC(O)OH and HC(O)OOH. United States: N. p., 2003. Web. doi:10.1021/jp021569k.
Feller, David F, Dixon, David A, & Francisco, Joseph. Coupled Cluster Theory Determination of the Heats of Formation of Combustion-related compounds: CO, HCO, CO2, HCO2, HOCO, HC(O)OH and HC(O)OOH. United States. doi:10.1021/jp021569k.
Feller, David F, Dixon, David A, and Francisco, Joseph. Wed . "Coupled Cluster Theory Determination of the Heats of Formation of Combustion-related compounds: CO, HCO, CO2, HCO2, HOCO, HC(O)OH and HC(O)OOH". United States. doi:10.1021/jp021569k.
@article{osti_15010162,
title = {Coupled Cluster Theory Determination of the Heats of Formation of Combustion-related compounds: CO, HCO, CO2, HCO2, HOCO, HC(O)OH and HC(O)OOH},
author = {Feller, David F and Dixon, David A and Francisco, Joseph},
abstractNote = {Coupled cluster theory through quasiperturbative, connected triple excitations (CCSD(T)) was used to obtain optimized structures, harmonic vibrational frequencies and heats of formation for seven related small molecules. For the three systems possessing reliable experimental heats of formation, the level of agreement between theory and experiment was excellent. In order to achieve this level of agreement and to simultaneously minimize the theoretical uncertainty it was necessary to apply large correlation consistent basis sets (through septuple zeta in some cases) followed by a number of small, but nonnegligible, energetic corrections. For CO, {Delta}H{sub f}{sup 0}(0 K) = -27.0 {+-} 0.2 (theory) vs -27.20 {+-} 0.04 kcal/mol (expt.). For CO{sub 2}, {Delta}H{sub f}{sup 0}(0 K) = -93.7 {+-} 0.2 (theory) vs -93.97 {+-} 0.01 kcal/mol (expt.). For HC(O)OH (formic acid), {Delta}H{sub f}{sup 0}(0 K) = -88.9 {+-} 0.4 (theory) vs -88.7 {+-} 0.1 kcal/mol (expt.). For HCO, the experimental and theoretical values are in near perfect agreement, with {Delta}H{sub f}{sup 0}(0 K = 10.4 {+-} 0.2 (theory) vs 10.3 {+-} 2 kcal/mol (expt.)), although this may be somewhat fortuitous since the experimental value is not very reliable. For trans-HOCO, we predict a value of {Delta}H{sub f}{sup 0}(0 K = -43.9 {+-} 0.5), compared to the revised photoionization value of {ge}45.8 {+-} 0.7 kcal/mol. Theory, however, is in good agreement with the possible experimental value of -42.7 {+-} 0.9 kcal/mol suggested in the same photoionization experimental analysis. For HCO{sub 2} and HC(O)OOH, where no experimental data exists, {Delta}H{sub f}{sup 0}(0 K = -27.6 {+-} 0.4 and -65.6 {+-} 0.6 kcal/mol respectively). trans-HOCO is only slightly bound (1.1 kcal/mol) with respect to the H + CO{sub 2} asymptote. HCO{sub 2} is 15.7 kcal/mol higher in energy than trans-HOCO and lies above the H + CO{sub 2} asymptote by 14.6 kcal/mol. It is only bound with respect to the OH + CO asymptote by 9.0 kcal/mol. Three parameterized methods (G2, G3 and CBS-Q) were compared to the best coupled cluster heats of formation and found to differ by up to 3.2 kcal/mol.},
doi = {10.1021/jp021569k},
journal = {Journal of Physical Chemistry A, 107(10):1604-1617},
number = ,
volume = ,
place = {United States},
year = {2003},
month = {2}
}