The molecular structure of cyclohexanone was calculated by the B3LYP density functional model with 6-31G(d,p)and 6-311++G(d,p)basis set by Gaussian program.The results from natural bond orbital(NBO)analysis have been ...The molecular structure of cyclohexanone was calculated by the B3LYP density functional model with 6-31G(d,p)and 6-311++G(d,p)basis set by Gaussian program.The results from natural bond orbital(NBO)analysis have been analyzed in terms of the hybridization of atoms and the electronic structure of the title molecule.The electron density based local reactivity descriptors such as Fukui functions were calculated.The dipole moment(μ)and polarizability(α),anisotropy polarizability(Δα)and first order hyperpolarizability(βtot)of the molecule have been reported.Thermodynamic properties of the title compound were calculated at different temperatures.展开更多
The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl2(L)2, where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl...The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl2(L)2, where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl2 (Azpy)2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium’s selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru) π*(N1-N2) does correspond to t2g?π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl2(Nazpy)2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.展开更多
The discovered in 2008 Fe-based superconductors (SC) are a paramagnetic semimetal at ambient temperature and in some cases they become superconductor upon doping. In spite of so many years since its discovery it is st...The discovered in 2008 Fe-based superconductors (SC) are a paramagnetic semimetal at ambient temperature and in some cases they become superconductor upon doping. In spite of so many years since its discovery it is still not known the mechanism that leads to superconductivity. The electronic structure study is used for determining key features of the SC mechanism in these materials. The calculations were performed using the modern suite of programs MOLPRO 2021. We performed quantum calculations of a cluster embedded in a background charge distribution that represents the infinite crystal. The Natural Population Analysis was used for determining the charge and spin distribution in the studied materials. As follows from our results, the possible mechanism for superconductivity corresponds to the RVB theory proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.展开更多
Analyses of chemical bonding and geometric structures in species with chalcogen elements EThF_2(E=O,S,Se,Te) are performed by the density functional theory. Kohn–Sham molecular orbitals and Th–E bond lengths of thes...Analyses of chemical bonding and geometric structures in species with chalcogen elements EThF_2(E=O,S,Se,Te) are performed by the density functional theory. Kohn–Sham molecular orbitals and Th–E bond lengths of these species both indicate multiple bond character for the terminal chalcogen complexes. This is also confirmed by natural bond orbital analyses using the oneelectron density matrix generated by relativistic density functional calculations. Theoretical analyses indicate that electron donation from E to Th increases down the chalcogen group(O<S<Se<Te). These molecules can serve as examples of multiple bonding between actinide elements and selenium or tellurium.展开更多
The optimized geometries and vibration frequencies of luteolin,methanol and luteolin-（CH3OH）n complexes have been investigated by density functional theory using B3LYP method.Four stable luteolin-CH3OH complexes,six...The optimized geometries and vibration frequencies of luteolin,methanol and luteolin-（CH3OH）n complexes have been investigated by density functional theory using B3LYP method.Four stable luteolin-CH3OH complexes,six stable luteolin-（CH3OH）2 complexes and four stable luteolin-（CH3OH）3 complexes have been obtained.The theories of atoms in molecules（AIM） and natural bond orbital（NBO） have been used to analyze the hydrogen bonds of these compounds,and their interaction energies corrected by basis set superposition error are between-8.046 and-76.124 kJ/mol.The calculation results indicate strong hydrogen bonding interactions in the luteolin-（CH3OH）n complexes.Then the nuclear magnetic resonance（NMR） and electronic absorption spectrum of luteolin have been calculated,and the results are in agreement with the experimental data.展开更多
Theoretical study of several O-nitrosyl carboxylate compounds have been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G^(**) basis set.Geometries obtained...Theoretical study of several O-nitrosyl carboxylate compounds have been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G^(**) basis set.Geometries obtained from DFT calculations were used to perform the natural bond orbital(NBO)analysis.It is noted that weakness in the O_(3)-N_(2) bond is due to nO_(1)→σO_(3)-N_(2) delocalization and is responsible for the longer O_(3)-N_(2) bond lengths in O-nitrosyl carboxylate compounds.It is also noted that decreased occupancy of the localized σO_(3)-N_(2) orbital in the idealized Lewis structure,or increased occupancy of σO_(3)-N_(2) of the non-Lewis orbital,and their subsequent impact on molecular stability and geometry(bond lengths)are related with the resulting p character of the corresponding sulfur natural hybrid orbital(NHO)of σ_(O_(3)-N_(2)) bond orbital.In addition,the charge transfer energy decreases with the increase of the Hammett constants of subsitutent groups.展开更多
The theoretical study of the dehydrogenation of 2,5-dihydro-[furan （1）, thiophene （2）, and selenophene （3）] was carried out using ab initio molecular orbital （MO） and density functional theory （DFT） methods ...The theoretical study of the dehydrogenation of 2,5-dihydro-[furan （1）, thiophene （2）, and selenophene （3）] was carried out using ab initio molecular orbital （MO） and density functional theory （DFT） methods at the B3LYP/6-311G＊＊//B3LYP/6-311G＊＊ and MP2/6-311G＊＊//B3LYP/6-311G＊＊ levels of theory. Among the used methods in this study, the obtained results show that B3LYP/6-311G＊＊ method is in good agreement with the available experimental values. Based on the optimized ground state geometries using B3LYP/6-311G＊＊ method, the natural bond orbital （NBO） analysis of donor-acceptor （bond-antibond） interactions revealed that the stabilization energies associated with the electronic delocalization from non-bonding lone-pair orbitals [LP（e）x3] to C＊C（1）- H（2） antibonding orbital, decrease from compounds 1 to 3. The LP（e）x3→σ＊c（1）-H（2） resonance energies for compounds 1--3 are 23.37, 16.05 and 12.46 kJ/mol, respectively. Also, the LP（e）xa→σ＊c（1）-H（2） delocalizations could fairly explain the decrease of occupancies of LP（e）x3 non-bonding orbitals in ring of compounds 1-3 （3 〉2 〉 1）. The electronic delocalization from LP（e）x3 non-bonding orbitals to σ＊c（1）-G（2） antibonding orbital increases the ground state structure stability, Therefore, the decrease of LP（e）x3→σ＊c（1）-H（2） delocalizations could fairly explain the kinetic of the dehydrogenation reactions of compounds 1-3 （kl〉k2〉k3）. Also, the donor-acceptor interactions, as obtained from NBO analysis, revealed that the πc（4）=c（7）→σ＊c（1）-H（2） resonance energies decrease from compounds 1 to 3. Further, the results showed that the energy gaps between πC（4）-C（7） bonding and σ＊c（1）-H（2） antibonding orbitals decrease from compounds 1 to 3. The results suggest also that in compounds 1--3, the hydrogen elimi- nations are controlled by LP（e）→σ＊ resonance energies. Analysis of bond order, natural bond orbital charges, bond indexes, synchronicity parameters, and IRC calculations indicate that these reactions are occurring through a con- certed and synchronous six-membered cyclic transition state type of mechanism.展开更多
文摘The molecular structure of cyclohexanone was calculated by the B3LYP density functional model with 6-31G(d,p)and 6-311++G(d,p)basis set by Gaussian program.The results from natural bond orbital(NBO)analysis have been analyzed in terms of the hybridization of atoms and the electronic structure of the title molecule.The electron density based local reactivity descriptors such as Fukui functions were calculated.The dipole moment(μ)and polarizability(α),anisotropy polarizability(Δα)and first order hyperpolarizability(βtot)of the molecule have been reported.Thermodynamic properties of the title compound were calculated at different temperatures.
文摘The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl2(L)2, where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl2 (Azpy)2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium’s selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru) π*(N1-N2) does correspond to t2g?π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl2(Nazpy)2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.
文摘The discovered in 2008 Fe-based superconductors (SC) are a paramagnetic semimetal at ambient temperature and in some cases they become superconductor upon doping. In spite of so many years since its discovery it is still not known the mechanism that leads to superconductivity. The electronic structure study is used for determining key features of the SC mechanism in these materials. The calculations were performed using the modern suite of programs MOLPRO 2021. We performed quantum calculations of a cluster embedded in a background charge distribution that represents the infinite crystal. The Natural Population Analysis was used for determining the charge and spin distribution in the studied materials. As follows from our results, the possible mechanism for superconductivity corresponds to the RVB theory proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.
基金supported by ‘‘Strategic Priority Research Program’’of the Chinese Academy of Sciences(No.XDA02020000)the National Natural Science Foundation of China(Nos.21573273,21501189)the support from Hundred Talents Program(CAS)
文摘Analyses of chemical bonding and geometric structures in species with chalcogen elements EThF_2(E=O,S,Se,Te) are performed by the density functional theory. Kohn–Sham molecular orbitals and Th–E bond lengths of these species both indicate multiple bond character for the terminal chalcogen complexes. This is also confirmed by natural bond orbital analyses using the oneelectron density matrix generated by relativistic density functional calculations. Theoretical analyses indicate that electron donation from E to Th increases down the chalcogen group(O<S<Se<Te). These molecules can serve as examples of multiple bonding between actinide elements and selenium or tellurium.
文摘The optimized geometries and vibration frequencies of luteolin,methanol and luteolin-（CH3OH）n complexes have been investigated by density functional theory using B3LYP method.Four stable luteolin-CH3OH complexes,six stable luteolin-（CH3OH）2 complexes and four stable luteolin-（CH3OH）3 complexes have been obtained.The theories of atoms in molecules（AIM） and natural bond orbital（NBO） have been used to analyze the hydrogen bonds of these compounds,and their interaction energies corrected by basis set superposition error are between-8.046 and-76.124 kJ/mol.The calculation results indicate strong hydrogen bonding interactions in the luteolin-（CH3OH）n complexes.Then the nuclear magnetic resonance（NMR） and electronic absorption spectrum of luteolin have been calculated,and the results are in agreement with the experimental data.
基金We gratefully thank the National Natural Science Foundation of China(Grant No.10774039)the grant from Development Program in Science and Technology of Henan Province(Grant No.102300410114)Foundation for University Key Teacher by the Ministry of Education of Henan Province,and Henan University of Science and Technology for Young Scholars(Grant No.2009QN0032)for their support of this work.
文摘Theoretical study of several O-nitrosyl carboxylate compounds have been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G^(**) basis set.Geometries obtained from DFT calculations were used to perform the natural bond orbital(NBO)analysis.It is noted that weakness in the O_(3)-N_(2) bond is due to nO_(1)→σO_(3)-N_(2) delocalization and is responsible for the longer O_(3)-N_(2) bond lengths in O-nitrosyl carboxylate compounds.It is also noted that decreased occupancy of the localized σO_(3)-N_(2) orbital in the idealized Lewis structure,or increased occupancy of σO_(3)-N_(2) of the non-Lewis orbital,and their subsequent impact on molecular stability and geometry(bond lengths)are related with the resulting p character of the corresponding sulfur natural hybrid orbital(NHO)of σ_(O_(3)-N_(2)) bond orbital.In addition,the charge transfer energy decreases with the increase of the Hammett constants of subsitutent groups.
文摘The theoretical study of the dehydrogenation of 2,5-dihydro-[furan （1）, thiophene （2）, and selenophene （3）] was carried out using ab initio molecular orbital （MO） and density functional theory （DFT） methods at the B3LYP/6-311G＊＊//B3LYP/6-311G＊＊ and MP2/6-311G＊＊//B3LYP/6-311G＊＊ levels of theory. Among the used methods in this study, the obtained results show that B3LYP/6-311G＊＊ method is in good agreement with the available experimental values. Based on the optimized ground state geometries using B3LYP/6-311G＊＊ method, the natural bond orbital （NBO） analysis of donor-acceptor （bond-antibond） interactions revealed that the stabilization energies associated with the electronic delocalization from non-bonding lone-pair orbitals [LP（e）x3] to C＊C（1）- H（2） antibonding orbital, decrease from compounds 1 to 3. The LP（e）x3→σ＊c（1）-H（2） resonance energies for compounds 1--3 are 23.37, 16.05 and 12.46 kJ/mol, respectively. Also, the LP（e）xa→σ＊c（1）-H（2） delocalizations could fairly explain the decrease of occupancies of LP（e）x3 non-bonding orbitals in ring of compounds 1-3 （3 〉2 〉 1）. The electronic delocalization from LP（e）x3 non-bonding orbitals to σ＊c（1）-G（2） antibonding orbital increases the ground state structure stability, Therefore, the decrease of LP（e）x3→σ＊c（1）-H（2） delocalizations could fairly explain the kinetic of the dehydrogenation reactions of compounds 1-3 （kl〉k2〉k3）. Also, the donor-acceptor interactions, as obtained from NBO analysis, revealed that the πc（4）=c（7）→σ＊c（1）-H（2） resonance energies decrease from compounds 1 to 3. Further, the results showed that the energy gaps between πC（4）-C（7） bonding and σ＊c（1）-H（2） antibonding orbitals decrease from compounds 1 to 3. The results suggest also that in compounds 1--3, the hydrogen elimi- nations are controlled by LP（e）→σ＊ resonance energies. Analysis of bond order, natural bond orbital charges, bond indexes, synchronicity parameters, and IRC calculations indicate that these reactions are occurring through a con- certed and synchronous six-membered cyclic transition state type of mechanism.
基金supported by the National Natural Science Foundation of China(10804027,11011140321)Natural Science Foundation of Education Department of Henan Province,China(2011A140003)~~
