Thanh Tâm - Academia.edu (original) (raw)
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Papers by Thanh Tâm
Accurate electronic structure calculations for C 6 H 6 + CH 3 /C 2 H 5 = C 6 H 5 + CH 4 /C 2 H... more Accurate electronic structure calculations for C 6 H 6 + CH 3 /C 2 H 5 = C 6 H 5 + CH 4 /C 2 H 6 reactions was studied with CCSD(T)/CBS//BH&HLYP/cc-pVDZ.
The mechanism for the reaction of HCCO and OH has been investigated at different high-levels of t... more The mechanism for the reaction of HCCO and OH has been investigated at different high-levels of theory. The reaction was found to occur on singlet and triplet potential energy surfaces with multiple accessible paths. Rate constants predicted by variational RRKM/ME calculations show that the reaction on both surfaces occurs primarily by barrierless OH attack at both C atoms producing excited intermediates which fragment to produce predominantly CO and 1,3 HCOH with k S = 3.12 Â 10 À8 T À0.59 exp[À73.0/T] and k T = 6.29 Â 10 À11 T 0.13 exp[108/T] cm 3 molecule À1 s À1 at T = 300–2000 K, independent of pressure at P < 76 000 Torr.
Accurate description of reactions between methyl acetate (MA) radicals and molecular oxygen is an... more Accurate description of reactions between methyl acetate (MA) radicals and molecular oxygen is an essential prerequisite for understanding as well as model-ing low-temperature oxidation and/or ignition of MA, a small biodiesel surrogate, because their multiple reaction pathways either accelerate the oxidation process via chain branching or inhibit it by forming relatively stable products. The accurate composite CBS-QB3 level of theory was used to explore potential energy surfaces for MA radicals ? O 2 system. Using the electronic structure calculation results under the framework of canonical statistical mechanics and transition state theory, thermodynamic properties of all species as well as high-pressure rate constants of all reaction channels were derived with explicit corrections for tunneling and hindered internal rotations. Our calculated results are in good agreement with a limited number of scattered data in the literature. Furthermore , pressure-and temperature-dependent rate constants were then computed using the Quantum Rice– Ramsperger–Kassel and the modified strong collision theories. This procedure resulted in a thermodynamically consistent detailed kinetic mechanism for low-temperature oxidation of the title fuel. We also demonstrated that even the detailed mechanism consists of several reactions of different reaction types, only the addition of the reactants and the re-dissociation of the initially formed adducts are important for low-temperature combustion at engine-liked conditions. Keywords Biodiesel surrogate Á Oxygenated hydrocarbon Á Alkyl peroxy radical Á Detailed kinetic model Á Low-temperature oxidation and ignition
Thermal rate constants of the CH 4 ? O 2 = CH 3 ? HO 2 reaction were calculated from first princi... more Thermal rate constants of the CH 4 ? O 2 = CH 3 ? HO 2 reaction were calculated from first principles using both the conventional transition state theory (TST) and canonical variational TST methods with correction from the explicit hindered rotation treatment. The CCSD(T)/ aug-cc-pVTZ//BH&HLYP/aug-cc-pVDZ method was used to characterize the necessary potential energy surface along the minimum energy path. We found that the correction for hindered rotation treatment, as well as the re-crossing effects noticeably affect the rate constants of the title process. The calculated rate constants for both forward and reverse directions are expressed in the modified Arrhenius form as k
Accurate electronic structure calculations for C 6 H 6 + CH 3 /C 2 H 5 = C 6 H 5 + CH 4 /C 2 H... more Accurate electronic structure calculations for C 6 H 6 + CH 3 /C 2 H 5 = C 6 H 5 + CH 4 /C 2 H 6 reactions was studied with CCSD(T)/CBS//BH&HLYP/cc-pVDZ.
The mechanism for the reaction of HCCO and OH has been investigated at different high-levels of t... more The mechanism for the reaction of HCCO and OH has been investigated at different high-levels of theory. The reaction was found to occur on singlet and triplet potential energy surfaces with multiple accessible paths. Rate constants predicted by variational RRKM/ME calculations show that the reaction on both surfaces occurs primarily by barrierless OH attack at both C atoms producing excited intermediates which fragment to produce predominantly CO and 1,3 HCOH with k S = 3.12 Â 10 À8 T À0.59 exp[À73.0/T] and k T = 6.29 Â 10 À11 T 0.13 exp[108/T] cm 3 molecule À1 s À1 at T = 300–2000 K, independent of pressure at P < 76 000 Torr.
Accurate description of reactions between methyl acetate (MA) radicals and molecular oxygen is an... more Accurate description of reactions between methyl acetate (MA) radicals and molecular oxygen is an essential prerequisite for understanding as well as model-ing low-temperature oxidation and/or ignition of MA, a small biodiesel surrogate, because their multiple reaction pathways either accelerate the oxidation process via chain branching or inhibit it by forming relatively stable products. The accurate composite CBS-QB3 level of theory was used to explore potential energy surfaces for MA radicals ? O 2 system. Using the electronic structure calculation results under the framework of canonical statistical mechanics and transition state theory, thermodynamic properties of all species as well as high-pressure rate constants of all reaction channels were derived with explicit corrections for tunneling and hindered internal rotations. Our calculated results are in good agreement with a limited number of scattered data in the literature. Furthermore , pressure-and temperature-dependent rate constants were then computed using the Quantum Rice– Ramsperger–Kassel and the modified strong collision theories. This procedure resulted in a thermodynamically consistent detailed kinetic mechanism for low-temperature oxidation of the title fuel. We also demonstrated that even the detailed mechanism consists of several reactions of different reaction types, only the addition of the reactants and the re-dissociation of the initially formed adducts are important for low-temperature combustion at engine-liked conditions. Keywords Biodiesel surrogate Á Oxygenated hydrocarbon Á Alkyl peroxy radical Á Detailed kinetic model Á Low-temperature oxidation and ignition
Thermal rate constants of the CH 4 ? O 2 = CH 3 ? HO 2 reaction were calculated from first princi... more Thermal rate constants of the CH 4 ? O 2 = CH 3 ? HO 2 reaction were calculated from first principles using both the conventional transition state theory (TST) and canonical variational TST methods with correction from the explicit hindered rotation treatment. The CCSD(T)/ aug-cc-pVTZ//BH&HLYP/aug-cc-pVDZ method was used to characterize the necessary potential energy surface along the minimum energy path. We found that the correction for hindered rotation treatment, as well as the re-crossing effects noticeably affect the rate constants of the title process. The calculated rate constants for both forward and reverse directions are expressed in the modified Arrhenius form as k