The process of graphene cleaning of a copper film by bombarding it with Ar_（13） clusters is investigated by the molecular dynamics method.The kinetic energies of the clusters are 5,10,20,and 30 eV and the incident a...The process of graphene cleaning of a copper film by bombarding it with Ar_（13） clusters is investigated by the molecular dynamics method.The kinetic energies of the clusters are 5,10,20,and 30 eV and the incident angles are θ= 90°,75°,60°,45°,and 0°.It is obtained that the cluster energy should be in the interval 20 eV-30 eV for effective graphene cleaning.There is no cleaning effect at vertical incidence（θ =0°） of Ar_（13） clusters.The bombardments at 45° and 90° incident angles are the most effective on a moderate and large amount of deposited copper,respectively.展开更多
The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dyna...The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dynamics simulation with consideration of the SWCNTs to be fixed. Since the diameters of SWCNTs with different chiralities increase when temperature is fixed at 20 K, the equilibrium structures of the argon cluster transform from monoatomic chains to helical and then to multishell coaxial cylinders. Chirality has almost no noticeable influence on these cylindrosymmetric structures. The effects of temperature and a non-equilibrium sudden heating process on the structures of argon clusters in SWCNTs are also studied by molecular dynamics simulation.展开更多
The ultimate aim of the present work is to establish an acceptable level of computation for the van der waals (vdw) complexes that is able to pick up appreciable amount of dispersion interaction energy, reproduce the ...The ultimate aim of the present work is to establish an acceptable level of computation for the van der waals (vdw) complexes that is able to pick up appreciable amount of dispersion interaction energy, reproduce the equilibrium separation within the acceptable limits and at the same time cost and time effective. In order to reach this aim vdw clusters where pure isotropic dispersion interaction occur, namely, Ar dimer and trime were investigated. Computations using different basis sets and at different levels of theory have been carried out. Three basis sets, namely, the 6-31++G**, the 6-311++G** and the aug-cc-pvdz basis set, were found superior to all other basis sets used. The high performance and relative small CPU time of the 6-31++G** basis set make it a good candidate for use with large vdw clusters, especially those of interest in biology. Three compound methods were applied in the present work, namely G1, G2 and G2 Moller-Plesset (MP2) and the complete basis set method, CBS-Q. These methods failed to detect the attraction dispersion interaction in the dimer. The predicted repulsive interaction seems dominant in all these methods. Some of the recently developed Density Functional Theory (DFT) methods that were parameterized to account for the dispersion interaction were also evaluated in the present work. Results come to the conclusion that, in contrast to the claims made, state-of-the-art Density Functional Theory methods are incapable of accounting for dispersion effects in a quantitative way, although these methods predict correctly the inter-atomic separations and are?thus considered a real improvement over the conventional methods. BS-SE has been computed, analyzed and discussed.展开更多
基金supported by the Russian Foundation for Basic Research(Grant No.13-08-00273)
文摘The process of graphene cleaning of a copper film by bombarding it with Ar_（13） clusters is investigated by the molecular dynamics method.The kinetic energies of the clusters are 5,10,20,and 30 eV and the incident angles are θ= 90°,75°,60°,45°,and 0°.It is obtained that the cluster energy should be in the interval 20 eV-30 eV for effective graphene cleaning.There is no cleaning effect at vertical incidence（θ =0°） of Ar_（13） clusters.The bombardments at 45° and 90° incident angles are the most effective on a moderate and large amount of deposited copper,respectively.
基金Project supported by the National Natural Science Foundation of China(Grant No.11072242)
文摘The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dynamics simulation with consideration of the SWCNTs to be fixed. Since the diameters of SWCNTs with different chiralities increase when temperature is fixed at 20 K, the equilibrium structures of the argon cluster transform from monoatomic chains to helical and then to multishell coaxial cylinders. Chirality has almost no noticeable influence on these cylindrosymmetric structures. The effects of temperature and a non-equilibrium sudden heating process on the structures of argon clusters in SWCNTs are also studied by molecular dynamics simulation.
文摘The ultimate aim of the present work is to establish an acceptable level of computation for the van der waals (vdw) complexes that is able to pick up appreciable amount of dispersion interaction energy, reproduce the equilibrium separation within the acceptable limits and at the same time cost and time effective. In order to reach this aim vdw clusters where pure isotropic dispersion interaction occur, namely, Ar dimer and trime were investigated. Computations using different basis sets and at different levels of theory have been carried out. Three basis sets, namely, the 6-31++G**, the 6-311++G** and the aug-cc-pvdz basis set, were found superior to all other basis sets used. The high performance and relative small CPU time of the 6-31++G** basis set make it a good candidate for use with large vdw clusters, especially those of interest in biology. Three compound methods were applied in the present work, namely G1, G2 and G2 Moller-Plesset (MP2) and the complete basis set method, CBS-Q. These methods failed to detect the attraction dispersion interaction in the dimer. The predicted repulsive interaction seems dominant in all these methods. Some of the recently developed Density Functional Theory (DFT) methods that were parameterized to account for the dispersion interaction were also evaluated in the present work. Results come to the conclusion that, in contrast to the claims made, state-of-the-art Density Functional Theory methods are incapable of accounting for dispersion effects in a quantitative way, although these methods predict correctly the inter-atomic separations and are?thus considered a real improvement over the conventional methods. BS-SE has been computed, analyzed and discussed.
