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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >An Alternative Mechanism for the Dimerization of Formic Acid
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An Alternative Mechanism for the Dimerization of Formic Acid

机译：甲酸二聚的另一种机制

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Gas-phase formic acid exists primarily as a cyclic dimer. The mechanism of dimerization has been traditionally considered to be a synchronous process; however, recent experimental findings suggest a possible alternative mechanism by which two formic acid monomers proceed through an acyclic dimer to the cyclic dimer in a stepwise process. To investigate this newly proposed process of dimerization in formic acid, density functional theory and second-order Moller-Plesset perturbation theory (MP2) have been used t optimize cis and trans monomers of formic acid, the acyclic and cyclic dimers, and the acyclic and cyclic transition states between minima. Single-point energies of the trans monomer, dimer minima, and transition states at the MP2/TZ2P+diff optimized geometries were computed at the coupled-cluster level of theory including singles and doubles with perturbatively applied triple excitations [CCSD(T)] with an aug'-cc-pVTZ basis set to obtain an accurate determination of energy barriers and dissociation energies. A counterpoise correction was performed to determine an estimate of the basis set superposition error in computing relative energies. The explicitly correlated MP2 method of Kutzelnigg and Klopper (MP2-R12) was used to provide an independent means for obtaining the MP2 one-particle limit. The cyclic minimum is predicted to be 6.3 kcal/mol more stable than the acyclic minimum, and the barrier to double proton transfer is 7.1 kcal/mol.
机译：气相甲酸主要以环状二聚体存在。传统上，二聚化机制被认为是一个同步过程。然而，最近的实验发现提示了一种可能的替代机制，通过该机制，两个甲酸单体可以逐步地通过无环二聚体进入环状二聚体。为了研究这种新提出的在甲酸中二聚的方法，已使用密度泛函理论和二阶Moller-Plesset微扰理论（MP2）来优化甲酸的顺式和反式单体，无环和环状二聚体以及无环和二聚体。极小值之间的循环过渡状态。 MP2 / TZ2P + diff优化的几何结构上反式单体的单点能量，二聚体最小值和跃迁态是在耦合簇理论水平下计算的，包括单扰和双扰以及扰动施加的三重激发[CCSD（T）]。 aug'-cc-pVTZ基集，可准确确定能垒和离解能。在计算相对能量时进行平衡平衡修正，以确定对基组叠加误差的估计。 Kutzelnigg和Klopper（MP2-R12）的显式关联MP2方法用于提供获得MP2单粒子限制的独立方法。预计循环最小值比无环最小值稳定6.3 kcal / mol，并且双质子转移的障碍为7.1 kcal / mol。

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