The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer mol...The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer molecular dynamics(RPMD)method on a full-dimensional potential energy surface(PES).This PES is the most accurate one for the title reaction,as demonstrated by the correct barrier height and reaction energy,compared to the benchmark calculations by the focal point analysis and the high accuracy extrapolated ab initio thermochemistry methods.The RPMD rate coefficients are in excellent agreement with those calculated by the semiclassical transition state theory and a two-dimensional master equation technique,and some experimental measurements.As has been found in many RPMD applications,quantum effects,including tunneling and zero-point energy effects,can be efficiently and effectively captured by the RPMD method.In addition,the convergence of the results with respect to the number of beads is rapid,which is also consistent with previous RPMD applications.展开更多
Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very g...Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very good descriptions of the regions around conical intersections and of van der Waals(vdW)interactions.The calculated reaction thermal rate coefficients are in very good agreement with the latest experimental results.The rate coefficients obtained from the ground˜a^(1)A′ZMB-a PES are much larger than those from the previous RKHS PES,which can be attributed to that the vdW saddles on our PESs have very different dynamical effects from the vdW wells on the previous PESs,indicating that the RPMD approach is able to include dynamical effects of the topological structures caused by vdW interactions.The importance of the excited˜b^(1)A′′ZMB-b PES and quantum effects in the title reaction is also underscored.展开更多
Although many ionic liquids have been reported, their polarity is not completely understood. Different empirical polarity scales for molecular solvents always lead to different polarity orders when they are applied on...Although many ionic liquids have been reported, their polarity is not completely understood. Different empirical polarity scales for molecular solvents always lead to different polarity orders when they are applied on ionic liquids. Based on a literature survey, this review summarizes the recent polarity scales of ionic liquids according to the following 4 classes:(1) equilibrium and kinetic rate constants of chemical reactions;(2) empirical polar parameters of ionic liquids;(3) spectral properties of probe molecules;(4) multiparameter approaches. In addition, their interrelations are presented. A systematic understanding of the relationship between different polarity parameters of ionic liquids is of great importance for finding a universal set of parameters that can be used to predict the polarities of ionic liquids quantitatively. The potential utilization of the electron paramagnetic resonance in this field is also addressed.展开更多
基金supported by the National Natural Science Foundation of China(No.21573027)
文摘The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer molecular dynamics(RPMD)method on a full-dimensional potential energy surface(PES).This PES is the most accurate one for the title reaction,as demonstrated by the correct barrier height and reaction energy,compared to the benchmark calculations by the focal point analysis and the high accuracy extrapolated ab initio thermochemistry methods.The RPMD rate coefficients are in excellent agreement with those calculated by the semiclassical transition state theory and a two-dimensional master equation technique,and some experimental measurements.As has been found in many RPMD applications,quantum effects,including tunneling and zero-point energy effects,can be efficiently and effectively captured by the RPMD method.In addition,the convergence of the results with respect to the number of beads is rapid,which is also consistent with previous RPMD applications.
基金supported by the National Natural Science Foundation of China(No.21773251 and No.21973098)the Youth Innovation Promotion Association CAS(No.2018045)the Beijing National Laboratory for Molecular Sciences。
文摘Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very good descriptions of the regions around conical intersections and of van der Waals(vdW)interactions.The calculated reaction thermal rate coefficients are in very good agreement with the latest experimental results.The rate coefficients obtained from the ground˜a^(1)A′ZMB-a PES are much larger than those from the previous RKHS PES,which can be attributed to that the vdW saddles on our PESs have very different dynamical effects from the vdW wells on the previous PESs,indicating that the RPMD approach is able to include dynamical effects of the topological structures caused by vdW interactions.The importance of the excited˜b^(1)A′′ZMB-b PES and quantum effects in the title reaction is also underscored.
基金supported by the National Natural Science Foundation of China (21573196)the Program for Zhejiang Leading Team of S&T Innovation (2011R50007)the Fundamental Research Funds of the Central Universities
文摘Although many ionic liquids have been reported, their polarity is not completely understood. Different empirical polarity scales for molecular solvents always lead to different polarity orders when they are applied on ionic liquids. Based on a literature survey, this review summarizes the recent polarity scales of ionic liquids according to the following 4 classes:(1) equilibrium and kinetic rate constants of chemical reactions;(2) empirical polar parameters of ionic liquids;(3) spectral properties of probe molecules;(4) multiparameter approaches. In addition, their interrelations are presented. A systematic understanding of the relationship between different polarity parameters of ionic liquids is of great importance for finding a universal set of parameters that can be used to predict the polarities of ionic liquids quantitatively. The potential utilization of the electron paramagnetic resonance in this field is also addressed.
