Second-order M ller-Plesset(MP2) and density functional theory(DFT) calculations have been carried out in order to investigate the structures and properties of dihydrogen-bonded CaH 2 HY(Y = CH 3,C 2 H 3,C 2 H,CN,and ...Second-order M ller-Plesset(MP2) and density functional theory(DFT) calculations have been carried out in order to investigate the structures and properties of dihydrogen-bonded CaH 2 HY(Y = CH 3,C 2 H 3,C 2 H,CN,and NC) complexes.Our calculations revealed two possible structures for CaH 2 in CaH 2 HY complexes:linear(I) and bent(II).The bond lengths,interaction energies,and strengths for H H interactions obtained by both MP2 and B3LYP methods are quite close to each other.It was found that the interaction energy decreases with increasing electron density at the Ca-H bond critical point.Atom-in-molecule(AIM) results show that for all of Ca-H H-Y interactions considered here,the Laplacian of the electron density at the H H bond critical point is positive,indicating the electrostatic nature of these Ca-H H-Y dihydrogen bonded systems.展开更多
Methanol adsorption in zeolite and phosphorus modified zeolite has been investigated within the cluster model framework of quantum chemical calculation. Full optimization and frequency analysis of all cluster model ha...Methanol adsorption in zeolite and phosphorus modified zeolite has been investigated within the cluster model framework of quantum chemical calculation. Full optimization and frequency analysis of all cluster model have been carried out using Gaussian 94 soft package with Hartree-Fock method and B3LYP, B3P86 hybrid methods of density functional theory at 3-2 1 G, 6-31G basis set level for hydrogen atoms and 6-31G+(d) basis set level for the other atoms performed on small cluster model for CH3OH, H3Al(OH)SiH2(H2PO4), H3Al(OH)SiH2(H3SiO4), H3Al(OH-CH3OH)SiH2(H2PO4) and H3Al(OHCH3OH)SiH2(H3SiO4). The results show that phosphorus grafting in the zeolite framework has modified the chemical environment in the vicinity of the zeolite bridging hydroxyl. Phosphorus modification can enhance the acid strength of zeolite bridging hydroxyl, which was suggested by the lengthening of zeolite bridging hydroxyl O-H bond and the increasing methanol adsorption energy. This may be favorable to the initial CH3OCH3 formation in the methanol to gasoline (MTG) process.展开更多
The reaction mechanism of (CH3)3CO with CO has been theoretically investigated using density-functional theory (DFT) calculations at B3LYP/6-31G* level. In order to get more reliable energy values the single-point ene...The reaction mechanism of (CH3)3CO with CO has been theoretically investigated using density-functional theory (DFT) calculations at B3LYP/6-31G* level. In order to get more reliable energy values the single-point energy is evaluated at CCSD (T)/6-31++G** level. The results show that the reaction is multi-channel and the reaction of (CH3)3CO radical with CO mostly produces (CH3)3C + CO2. The reaction could play a role in eliminating air pollution.展开更多
基金supported by the National Natural Science Foundation of China (20973076,20703021)the Basic Science Research Funding of Jilin University
文摘Second-order M ller-Plesset(MP2) and density functional theory(DFT) calculations have been carried out in order to investigate the structures and properties of dihydrogen-bonded CaH 2 HY(Y = CH 3,C 2 H 3,C 2 H,CN,and NC) complexes.Our calculations revealed two possible structures for CaH 2 in CaH 2 HY complexes:linear(I) and bent(II).The bond lengths,interaction energies,and strengths for H H interactions obtained by both MP2 and B3LYP methods are quite close to each other.It was found that the interaction energy decreases with increasing electron density at the Ca-H bond critical point.Atom-in-molecule(AIM) results show that for all of Ca-H H-Y interactions considered here,the Laplacian of the electron density at the H H bond critical point is positive,indicating the electrostatic nature of these Ca-H H-Y dihydrogen bonded systems.
基金the Doctor’s Foundation of University of Petroleum
文摘Methanol adsorption in zeolite and phosphorus modified zeolite has been investigated within the cluster model framework of quantum chemical calculation. Full optimization and frequency analysis of all cluster model have been carried out using Gaussian 94 soft package with Hartree-Fock method and B3LYP, B3P86 hybrid methods of density functional theory at 3-2 1 G, 6-31G basis set level for hydrogen atoms and 6-31G+(d) basis set level for the other atoms performed on small cluster model for CH3OH, H3Al(OH)SiH2(H2PO4), H3Al(OH)SiH2(H3SiO4), H3Al(OH-CH3OH)SiH2(H2PO4) and H3Al(OHCH3OH)SiH2(H3SiO4). The results show that phosphorus grafting in the zeolite framework has modified the chemical environment in the vicinity of the zeolite bridging hydroxyl. Phosphorus modification can enhance the acid strength of zeolite bridging hydroxyl, which was suggested by the lengthening of zeolite bridging hydroxyl O-H bond and the increasing methanol adsorption energy. This may be favorable to the initial CH3OCH3 formation in the methanol to gasoline (MTG) process.
文摘The reaction mechanism of (CH3)3CO with CO has been theoretically investigated using density-functional theory (DFT) calculations at B3LYP/6-31G* level. In order to get more reliable energy values the single-point energy is evaluated at CCSD (T)/6-31++G** level. The results show that the reaction is multi-channel and the reaction of (CH3)3CO radical with CO mostly produces (CH3)3C + CO2. The reaction could play a role in eliminating air pollution.
