We present an efficient algorithm for calculating the minimum energy path(MEP)and energy barriers between local minima on a multidimensional potential energy surface(PES).Such paths play a central role in the understa...We present an efficient algorithm for calculating the minimum energy path(MEP)and energy barriers between local minima on a multidimensional potential energy surface(PES).Such paths play a central role in the understanding of transition pathways between metastable states.Our method relies on the original formulation of the string method[Phys.Rev.B,66,052301(2002)],i.e.to evolve a smooth curve along a direction normal to the curve.The algorithm works by performing minimization steps on hyperplanes normal to the curve.Therefore the problem of finding MEP on the PES is remodeled as a set of constrained minimization problems.This provides the flexibility of using minimization algorithms faster than the steepest descent method used in the simplified string method[J.Chem.Phys.,126(16),164103(2007)].At the same time,it provides a more direct analog of the finite temperature string method.The applicability of the algorithm is demonstrated using various examples.展开更多
High-temperature reactions widely exist in nature.However,they are difficult to characterize either experimentally or computationally.The minimum energy path(MEP)model routinely used in computational modeling of chemi...High-temperature reactions widely exist in nature.However,they are difficult to characterize either experimentally or computationally.The minimum energy path(MEP)model routinely used in computational modeling of chemical reactions is not justified to describe high-temperature reactions since high-energy structures are actively involved at high temperatures.In this study,we used methane(CH4)decomposition on Cu(111)surface as an example to compare systematically results obtained from the MEP model with those obtained from an explicit sampling of all relevant structures via ab initio molecular dynamics(AIMD)simulations at different temperatures.Interestingly,we found that,for reactions protected by strong steric hindrance effects,the MEP was still followed effectively even at a temperature close to the Cu melting point.In contrast,without such protection,the flexibility of the surface Cu atoms could lead to a significant reduction of the free-energy barrier at a high temperature.Accordingly,some earlier conclusions made about graphene growth mechanisms based on MEP calculations should be revisited.The physical insights provided by this study could deepen our understanding of high-temperature surface reactions.展开更多
基金support by the Department of Energy under Grant No.DE-SC0002623.
文摘We present an efficient algorithm for calculating the minimum energy path(MEP)and energy barriers between local minima on a multidimensional potential energy surface(PES).Such paths play a central role in the understanding of transition pathways between metastable states.Our method relies on the original formulation of the string method[Phys.Rev.B,66,052301(2002)],i.e.to evolve a smooth curve along a direction normal to the curve.The algorithm works by performing minimization steps on hyperplanes normal to the curve.Therefore the problem of finding MEP on the PES is remodeled as a set of constrained minimization problems.This provides the flexibility of using minimization algorithms faster than the steepest descent method used in the simplified string method[J.Chem.Phys.,126(16),164103(2007)].At the same time,it provides a more direct analog of the finite temperature string method.The applicability of the algorithm is demonstrated using various examples.
基金supported by NSFC(21825302)MOST(2016YFA0200604)by USTC-SCC,Tianjin,and Guangzhou Supercomputer Centers.
文摘High-temperature reactions widely exist in nature.However,they are difficult to characterize either experimentally or computationally.The minimum energy path(MEP)model routinely used in computational modeling of chemical reactions is not justified to describe high-temperature reactions since high-energy structures are actively involved at high temperatures.In this study,we used methane(CH4)decomposition on Cu(111)surface as an example to compare systematically results obtained from the MEP model with those obtained from an explicit sampling of all relevant structures via ab initio molecular dynamics(AIMD)simulations at different temperatures.Interestingly,we found that,for reactions protected by strong steric hindrance effects,the MEP was still followed effectively even at a temperature close to the Cu melting point.In contrast,without such protection,the flexibility of the surface Cu atoms could lead to a significant reduction of the free-energy barrier at a high temperature.Accordingly,some earlier conclusions made about graphene growth mechanisms based on MEP calculations should be revisited.The physical insights provided by this study could deepen our understanding of high-temperature surface reactions.
