Stirling András, Iannuzzi Marcella, Laio Alessandro, Parrinello Michele
Computational Science, Department of Chemistry and Applied Biosciences ETH Zurich, USI Campus, Via Giuseppe Buffi 13, 6900 Lugano, Switzerland.
Chemphyschem. 2004 Oct 18;5(10):1558-68. doi: 10.1002/cphc.200400063.
We studied the thermal intramolecular and radical rearrangement of azulene to naphthalene by employing a novel metadynamics method based on Car-Parrinello molecular dynamics. We demonstrate that relatively short simulations can provide us with several possible reaction mechanisms for the rearrangement. We show that different choices of the collective coordinates can steer the reaction along different pathways, thus offering the possibility of choosing the most probable mechanism. We consider herein three intramolecular mechanisms and two radical pathways. We found the norcaradiene pathway to be the preferable intramolecular mechanism, whereas the spiran mechanism is the favored radical route. We obtained high activation energies for all the intramolecular pathways (81.5-98.6 kcal mol(-1)), whereas the radical routes have activation energies of 24-39 kcal mol(-1). The calculations have also resulted in elementary steps and intermediates not yet considered. A few attractive features of the metadynamics method in studying chemical reactions are pointed out.
我们采用基于Car-Parrinello分子动力学的新型元动力学方法，研究了薁向萘的热分子内重排和自由基重排。我们证明，相对较短的模拟可以为我们提供重排的几种可能反应机制。我们表明，集体坐标的不同选择可以引导反应沿着不同的途径进行，从而提供了选择最可能机制的可能性。我们在此考虑三种分子内机制和两种自由基途径。我们发现降蒈二烯途径是更可取的分子内机制，而螺环机制是更有利的自由基途径。我们获得了所有分子内途径的高活化能（81.5 - 98.6千卡摩尔⁻¹），而自由基途径的活化能为24 - 39千卡摩尔⁻¹。计算还得出了尚未考虑的基元步骤和中间体。文中指出了元动力学方法在研究化学反应中的一些吸引人的特点。
