Density Functional Theory (DFT) studies on the ground states (2A'2) of NO3 radical and on the ground state (1A1') and the first triplet state (3E') of NO3+ cation provide an unambiguous prediction about th...Density Functional Theory (DFT) studies on the ground states (2A'2) of NO3 radical and on the ground state (1A1') and the first triplet state (3E') of NO3+ cation provide an unambiguous prediction about their geometrical structure-, the ground states of both NO3 radical and NO3+ cation have D3h symmetry and the geometrical configuration of the first triplet state 3E' of NO3+ cation has C2v symmetry. It is shown that as far as the ionization energy calculations on NO, radical are concerned, the results are only slightly different, no mater that gradient corrections of the exchange-correlation energy are included during self-consistent iterations or they are included as perturbations after the self-consistent iterations.展开更多
The magneto-structural correlation between a Mn(II) ion, coordinated in an octahe-dral environment, and two nitronyl nitroxide radical ligands in trans- and cis-metal-radical com-plexes is investigated by the broken s...The magneto-structural correlation between a Mn(II) ion, coordinated in an octahe-dral environment, and two nitronyl nitroxide radical ligands in trans- and cis-metal-radical com-plexes is investigated by the broken symmetry (BS) approach within density functional theory (DFT). The dependences of coupling constants J on three structural parameters: (i) bond angle θ (Mn-O-N (nitroxide)); (ii) rotating angle ψ, defined by the nitronyl nitroxide radical plane rotating around the axial Mn-O (nitroxide); (iii) bond distance R (Mn-O (nitroxide)) are directly calculated. Our calculations showed that both trans- and cis-Mn(II)-radical complexes behave a stronger antiferromagnetic interaction, consistent with experiments. In view of molecular orbital theory, the direct exchanges, including σ-type and π-type exchanges, are responsible for the magnetic ex-change pathways. There is a preferable linear correlation between the calculated coupling con-stants J and the overlap integral squares Sa2b between the local magnetic orbitals at the various rotating angle ψ at the fixed bond angle θ and bond distance R, in both trans- and cis-Mn(II)- radical complexes.展开更多
在B3LYP/6-31++G**水平下,对氧化呋咱单体及二聚体进行了几何构型优化,发现在由单体结合形成二聚体的过程中,子分子的平面构型并没有发生改变。通过振动频率分析结果推测出,分子中形成较大的π-π共轭,对C-H键的振动频率有影响,使得C-H...在B3LYP/6-31++G**水平下,对氧化呋咱单体及二聚体进行了几何构型优化,发现在由单体结合形成二聚体的过程中,子分子的平面构型并没有发生改变。通过振动频率分析结果推测出,分子中形成较大的π-π共轭,对C-H键的振动频率有影响,使得C-H伸缩频率发生了略微的红移,强度也明显增强。分子中原子(atoms in molecular,AIM)理论得出C-H共价键键临界点处电子密度的Laplacian值■2ρ具有负值。而O…H与N…H键临界点处2ρ都是大于零的,表明氧化呋咱二聚体中的O…H与N…H符合一般氢键的拓扑特点。二聚体在C-H键临界点处聚积电子的能力增强。运用渐近修正的SAPT(DFT)方法(symmetry-adapted perturbationtheory employing density functional theory),对氧化呋咱二聚体分子间作用进行能量分割。其中二聚体的静电能分别为-30.10kJ.mol-1和-37.36kJ.mol-1,与总的作用能相当,这也从侧面反映了氧化呋咱二聚体中分子中氢键作用主要由静电能决定。展开更多
简要介绍了近年来国内外分子间相互作用的理论状况与进展,主要是超分子方法(SM)、对称性匹配微扰理论(SAPT)、密度泛函理论(DFT)、定域相关方法及多种方法的结合对分子间相互作用的研究。在计算与模拟精确势能面(PES)时,超分子方法与微...简要介绍了近年来国内外分子间相互作用的理论状况与进展,主要是超分子方法(SM)、对称性匹配微扰理论(SAPT)、密度泛函理论(DFT)、定域相关方法及多种方法的结合对分子间相互作用的研究。在计算与模拟精确势能面(PES)时,超分子方法与微扰方法有效的结合,可以相互补充。SAPT与DFT的结合正在成为分子间作用理论的一种新近趋势。定域相关方法是一种选择性超分子方法,正在向更高水平的Mφller-P lesset微扰理论方向发展。当前对反映分子间主要电子相关效应的色散项的描述和计算仍有一定困难,并有相当挑战性。此外,阐述了分子间作用计算中所出现的基组问题,包括基组叠加误差及其均衡校正方案(counterpoise procedure,CP)存在的争议和基组饱和(basis set saturation)问题。展开更多
基金This work was supported by the National Natural Science Foundation of China （No.201374028 and No.21306034）, the Natural Science Foundation of Hebei Province （No.B2014201103）, and the Natural Science Foundation of Education Committee of Hebei Province （No.QN20131079）.
基金Project (No. 29673049) supported by the National Natural Sience Foundation of China.
文摘Density Functional Theory (DFT) studies on the ground states (2A'2) of NO3 radical and on the ground state (1A1') and the first triplet state (3E') of NO3+ cation provide an unambiguous prediction about their geometrical structure-, the ground states of both NO3 radical and NO3+ cation have D3h symmetry and the geometrical configuration of the first triplet state 3E' of NO3+ cation has C2v symmetry. It is shown that as far as the ionization energy calculations on NO, radical are concerned, the results are only slightly different, no mater that gradient corrections of the exchange-correlation energy are included during self-consistent iterations or they are included as perturbations after the self-consistent iterations.
基金supported by the National Natural Science Foundation of China(Grant Nos.20273005,20490210,NSFC/RGC 20318001)the Doctoral Program Foundation of the Ministry of Education(Grant No.20030001066).
文摘The magneto-structural correlation between a Mn(II) ion, coordinated in an octahe-dral environment, and two nitronyl nitroxide radical ligands in trans- and cis-metal-radical com-plexes is investigated by the broken symmetry (BS) approach within density functional theory (DFT). The dependences of coupling constants J on three structural parameters: (i) bond angle θ (Mn-O-N (nitroxide)); (ii) rotating angle ψ, defined by the nitronyl nitroxide radical plane rotating around the axial Mn-O (nitroxide); (iii) bond distance R (Mn-O (nitroxide)) are directly calculated. Our calculations showed that both trans- and cis-Mn(II)-radical complexes behave a stronger antiferromagnetic interaction, consistent with experiments. In view of molecular orbital theory, the direct exchanges, including σ-type and π-type exchanges, are responsible for the magnetic ex-change pathways. There is a preferable linear correlation between the calculated coupling con-stants J and the overlap integral squares Sa2b between the local magnetic orbitals at the various rotating angle ψ at the fixed bond angle θ and bond distance R, in both trans- and cis-Mn(II)- radical complexes.
文摘结合对称性破损(BS)方法,采用不同的密度泛函理论(DFT)对反铁磁性μ-1,3-N3-Ni(II)叠氮配合物[LNi2(N3)](Cl O4)2(L=pyrazolate)的磁特性进行了研究.结果显示,杂化密度泛函理论(HDFT)的计算结果与实验数据非常吻合,能够准确描述配合物的磁特性.磁轨道研究结果表明,配合物表现出较大的单占据轨道能量劈裂(0.93-0.99 e V),显示配合物的单占据轨道去简并化程度较大,且配合物中的2个磁通道(叠氮基、配体pyrazolate)中都分别存在有氮原子之间的p轨道重叠,这些都使得体系表现为反铁磁耦合作用.另外,配合物的磁性与叠氮桥和两金属离子间形成的二面角(τ,Ni-N-N-N-Ni)密切相关,τ从-55.38°逐渐变化到-1.5°的过程中,其反铁磁性逐渐增强,交换耦合常数(Jab)的绝对值逐渐增大,并在-11.95°处达到最大值(Jab=-151.02 cm-1).在此过程中,配合物中叠氮桥及其所连接的2个Ni离子与pyrazolate基配体L-中的2个桥原子N(4)、N(5)形成的七元环共平面性不断增强,即共平面性会诱导增强体系的反铁磁相互作用.
文摘在B3LYP/6-31++G**水平下,对氧化呋咱单体及二聚体进行了几何构型优化,发现在由单体结合形成二聚体的过程中,子分子的平面构型并没有发生改变。通过振动频率分析结果推测出,分子中形成较大的π-π共轭,对C-H键的振动频率有影响,使得C-H伸缩频率发生了略微的红移,强度也明显增强。分子中原子(atoms in molecular,AIM)理论得出C-H共价键键临界点处电子密度的Laplacian值■2ρ具有负值。而O…H与N…H键临界点处2ρ都是大于零的,表明氧化呋咱二聚体中的O…H与N…H符合一般氢键的拓扑特点。二聚体在C-H键临界点处聚积电子的能力增强。运用渐近修正的SAPT(DFT)方法(symmetry-adapted perturbationtheory employing density functional theory),对氧化呋咱二聚体分子间作用进行能量分割。其中二聚体的静电能分别为-30.10kJ.mol-1和-37.36kJ.mol-1,与总的作用能相当,这也从侧面反映了氧化呋咱二聚体中分子中氢键作用主要由静电能决定。
文摘简要介绍了近年来国内外分子间相互作用的理论状况与进展,主要是超分子方法(SM)、对称性匹配微扰理论(SAPT)、密度泛函理论(DFT)、定域相关方法及多种方法的结合对分子间相互作用的研究。在计算与模拟精确势能面(PES)时,超分子方法与微扰方法有效的结合,可以相互补充。SAPT与DFT的结合正在成为分子间作用理论的一种新近趋势。定域相关方法是一种选择性超分子方法,正在向更高水平的Mφller-P lesset微扰理论方向发展。当前对反映分子间主要电子相关效应的色散项的描述和计算仍有一定困难,并有相当挑战性。此外,阐述了分子间作用计算中所出现的基组问题,包括基组叠加误差及其均衡校正方案(counterpoise procedure,CP)存在的争议和基组饱和(basis set saturation)问题。
