Nagy Tibor, Yosa Reyes Juvenal, Meuwly Markus
Department of Chemistry, University of Basel , 4056 Basel, Switzerland.
J Chem Theory Comput. 2014 Apr 8;10(4):1366-75. doi: 10.1021/ct400953f. Epub 2014 Mar 21.
Adiabatic reactive molecular dynamics (ARMD) simulation method is a surface-crossing algorithm for modeling chemical reactions in classical molecular dynamics simulations using empirical force fields. As the ARMD Hamiltonian is time dependent during crossing, it allows only approximate energy conservation. In the current work, the range of applicability of conventional ARMD is explored, and a new multisurface ARMD (MS-ARMD) method is presented, implemented in CHARMM and applied to the vibrationally induced photodissociation of sulfuric acid (H2SO4) in the gas phase. For this, an accurate global potential energy surface (PES) involving 12 H2SO4 and 4 H2O + SO3 force fields fitted to MP2/6-311G++(2d,2p) reference energies is employed. The MS-ARMD simulations conserve total energy and feature both intramolecular H-transfer reactions and water elimination. An analytical treatment of the dynamics in the crossing region finds that conventional ARMD can approximately conserve total energy for limiting cases. In one of them, the reduced mass of the system is large, which often occurs for simulations of solvated biomolecular systems. On the other hand, MS-ARMD is a general approach for modeling chemical reactions including gas-phase, homogeneous, heterogeneous, and enzymatic catalytic reactions while conserving total energy in atomistic simulations.
绝热反应分子动力学（ARMD）模拟方法是一种用于在经典分子动力学模拟中使用经验力场对化学反应进行建模的表面穿越算法。由于ARMD哈密顿量在穿越过程中随时间变化，它仅允许近似的能量守恒。在当前工作中，探索了传统ARMD的适用范围，并提出了一种新的多表面ARMD（MS-ARMD）方法，该方法在CHARMM中实现，并应用于气相中硫酸（H2SO4）的振动诱导光解离。为此，采用了一个精确的全局势能面（PES），它涉及12个H2SO4和4个H2O + SO3力场，并拟合到MP2/6-311G++(2d,2p)参考能量。MS-ARMD模拟能够守恒总能量，并具有分子内H转移反应和水消除的特征。对穿越区域动力学的解析处理发现，传统ARMD在极限情况下可以近似守恒总能量。其中一种情况是，系统的约化质量很大，这在溶剂化生物分子系统的模拟中经常出现。另一方面，MS-ARMD是一种在原子模拟中守恒总能量的同时对化学反应进行建模的通用方法，包括气相、均相、非均相和酶催化反应。
