本文使用第一性原理计算方法研究了极性苯分子4-氰基苯胺和4,5-二氨基邻苯二腈夹钒原子三明治团簇的结构和磁学性质。计算结果表明三明治团簇中极性苯分子以反铁电形式排列,且钒–钒平均间距随着分子层数的增加显著减小。团簇的热力学稳定性随着分子层数的增加逐渐减小,但迅速趋于平稳。极性苯分子构成的团簇呈现半金属或者是金属性质,而它们的磁基态及其稳定性强烈地依赖于分子层数,这与苯分子构成的团簇存在很大的差异。本文的研究结果对于调控有机分子和过渡金属原子复合物的磁电特性具有重要的借鉴作用。
In this paper, the structural and magnetic properties are studied by the first-principle method for the sandwich clusters consisted of polar benzene molecules 4-cyananiline and 4, 5-diamino-phthalonitrile with vanadium. The calculated results show that the polar benzene molecules in the sandwich cluster are arranged in the antiferroelectric form, and the average vanadium-vanadium spacing decreases significantly with the increase of molecular layer number. The thermal stability of the cluster decreases gradually with the increase of molecular layer number, but tends to be stable rapidly. The clusters containing polar molecules exhibit a half-metallic or metallic property, and their magnetic ground states, as well as their stability, are strongly dependent on the number of molecular layers, which is very different from those containing benzene molecule. The results of this study are useful for regulating the magnetoelectric properties of organic molecules and transition metal complexes.
第一性原理,三明治团簇,过渡金属,极性分子,磁性, First Principle Sandwich Cluster Transition Metal Polar Molecule Magnetism摘要
1Faculty of Physics and Electronic Technology, Hubei University, Wuhan Hubei
2School of Materials Science and Engineering, Hubei University, Wuhan Hubei
Received: Mar. 25th, 2021; accepted: Apr. 29th, 2021; published: May 6th, 2021
ABSTRACT
In this paper, the structural and magnetic properties are studied by the first-principle method for the sandwich clusters consisted of polar benzene molecules 4-cyananiline and 4, 5-diamino-phthalonitrile with vanadium. The calculated results show that the polar benzene molecules in the sandwich cluster are arranged in the antiferroelectric form, and the average vanadium-vanadium spacing decreases significantly with the increase of molecular layer number. The thermal stability of the cluster decreases gradually with the increase of molecular layer number, but tends to be stable rapidly. The clusters containing polar molecules exhibit a half-metallic or metallic property, and their magnetic ground states, as well as their stability, are strongly dependent on the number of molecular layers, which is very different from those containing benzene molecule. The results of this study are useful for regulating the magnetoelectric properties of organic molecules and transition metal complexes.
为了研究VmBzn、Vm(C7N2H6)n、Vm(C8N4H6)n(m = 1~4, n = m + 1)三种三明治团簇的热力学稳定性,我们计算了m = 1~4层各基态结构的结合能,团簇的结合能E(m, n)定义如下 [4]:
E ( m , n ) = { m E [ V ] + n E [ X ] − E [ V m X n ] } / m
其中,m代表钒原子数,n代表配体分子数,E[V]代表优化后的钒原子能量,E[X]代表三种配体benzene分子、C7N2H6分子、以及C8N4H6分子优化后的能量,E[VmXn]代表优化后VmBzn、Vm(C7N2H6)n、Vm(C8N4H6)n (m = 1~4, n = m + 1)团簇结构的能量。计算得到的结合能如图3(a)所示。从图中我们可以看到各层结构得到的结合能均为正值,说明团簇结合过程是放热过程,因而团簇结构具有较强的稳定性。两种极性分子构型的团簇随着层数的增加,结合能逐渐减小,但是减小的速度明显放缓,并且V4(C8N4H6)5结合能有较小幅度的回升。我们可以预判,随着层数的增加,减小的速度会更小,推广到无限长的一维纳米线结构在热力学上也是稳定的。对于两种极性分子构成的三明治团簇结构在相同的层数时,Vm(C8N4H6)n结构较于Vm(C7N2H6)n结构结合能较小,说明在相同层数时,单CN分子和钒组成的三明治团簇结构更加稳定。
图3. Vm(Bz)n、Vm(C7N2H6)n和Vm(C8N4H6)n(m = 1~4, n = m + 1)三明治团簇的结合能(a)和能隙(b)
Ground magnetic state (GMS), energy difference between AFM and FM states (ΔEAFM-FM), and total magnetic moment (TMM) for a series of Vm(Bz)n, Vm(C7N2H6)n and Vm(C8N4H6)n (n = 1~4, m = n + 1) sandwich cluster
SWC
GMS
ΔEAFM-FM(meV)
TMM (μB)
V(Bz)2
FM
—
1.001
V2(Bz)3
FM
16.24
2.003
V3(Bz)4
FM
19.97
2.996
V4(Bz)5
FM
18.15
4.005
V(C7N2H6)2
FM
—
1.003
V2(C7N2H6)3
AFM
-0.76
0
V3(C7N2H6)4
FM
41.09
3.003
V4(C7N2H6)5
FM
72.98
3.995
V(C8N4H6)2
FM
—
0.999
V2(C8N4H6)3
AFM
-2.75
0.001
V3(C8N4H6)4
FM
48.44
2.999
V4(C8N4H6)5
FM
84.79
4.006
表2. Vm(Bz)n、Vm(C7N2H6)n和Vm(C8N4H6)n(m = 1~4, n = m + 1)三明治团簇的基态、铁磁和反铁磁态能量差、以及总磁矩
本文采用第一性原理计算方法对比研究了VmBzn、Vm(C7N2H6)n、以及Vm(C8N4H6)n(n = 1~4, m = n + 1)三明治团簇的结构和磁学性质。计算结果表明C7N2H6和C8N4H6构成的团簇中极性苯分子呈反铁电排列。随着三明治团簇层数的增加,配体为苯分子的团簇中钒–钒平均间距变化不大,而配体为极性苯分子构成的团簇中钒–钒平均间距明显减小,且C8N4H6形成的团簇中钒–钒平均间距减小的趋势最为明显。这是由于带正电的官能团-NH2和带负电的官能团-CN相互吸引所导致的结果。团簇的结合能均为较大正值,说明团簇具有热力学稳定性。我们还发现Vm(C7N2H6)n和Vm(C8N4H6)n团簇在n = 2,4,5时呈现铁磁基态,而n = 3时为反铁磁基态。电子态密度的结果清晰地显示团簇呈现出半金属或者金属态,其中钒原子的3d轨道以及碳和氮原子的2p轨道在费米能级处具有重要的贡献。
致谢
感谢湖北大学杨辉博士的讨论与交流。
基金项目
本研究得到了国家自然科学基金(批准号:11674087)的资助。
文章引用
宋叶刚,方世超,高 云,黄忠兵. 4-氰基苯胺和4,5-二氨基邻苯二腈夹钒原子三明治团簇的结构和磁学性质Structural and Magnetic Properties of Sandwich Clusters Consisted of Vanadium and 4-Aminobenzonitrile and 4,5-Diaminophthalonitrile[J]. 凝聚态物理学进展, 2021, 10(02): 56-65. https://doi.org/10.12677/CMP.2021.102007
参考文献ReferencesKealy, T.J. and Pauson, P.L. (1951) A New Type of Organo-Iron Compound. Nature, 168, 1039-1040.
<br>https://doi.org/10.1038/1681039b0Hoshino, K., Kurikawa, T., Takeda, H., Nakajima, A. and Kaya, K. (1995) Structures and Ionization Energies of Sandwich Clusters (V<sub>n</sub>(benzene)<sub>m</sub>). The Journal of Physical Chemistry, 99, 3053-3055.
<br>https://doi.org/10.1021/j100010a013Kurikawa, T., Negishi, Y., Hayakawa, F., Nagao, S., Miyajima, K., Nakajima, A., Kaya, K. and Kaya, K. (1998) Multiple-Decker Sandwich Complexes of Lantha-nide-1,3,5,7-Cyclooctatetraene [Ln<sub>n</sub>(C<sub>8</sub>H<sub>8</sub>)<sub>m</sub>] (Ln = Ce, Nd, Eu, Ho, and Yb); Localized Ionic Bonding Structure. Journal of the American Chemical Society, 120, 11766-11772.
<br>https://doi.org/10.1021/ja982438tLi, Y., Zhou, Z. and Chen, Z. (2012) From Vanadium Naphthalene (V<sub>n−1</sub>Np<sub>n</sub>) Sandwich Clusters to VNp Sandwich Nanowire: Structural, Energetic, Electronic, and Magnetic Properties. The Journal of Physical Chemistry A, 116, 1648- 1654. <br>https://doi.org/10.1021/jp2099398Masubuchi, T., Iwasa, T. and Nakajima, A. (2014) Experimental and Theoretical Studies of the Structural and Electronic Properties of Vanadium-Benzene Sandwich Clusters and Their Anions: V<sub>n</sub>Bz<sub>n</sub><sup>0/-</sup>
(n = 1-5) and V<sub>n</sub>Bz<sub>n-1</sub><sup>0/-</sup> (n = 2-5). The Journal of Physical Chemistry A, 141, Article ID: 214304.Maslyuk, V.V., Bagrets, A., Meded, V., Arnold, A., Evers, F., Brandbyge, M., Bredow, T. and Mertig, I. (2006) Organometallic Benzene-Vanadium Wire: A One-Dimensional Half-Metallic Ferromagnet. Physical Review Letters, 97, Article ID: 097201. <br>https://doi.org/10.1103/PhysRevLett.97.097201Rahman, M.M., Kasai, H. and Dy, E.S. (2005) Theoretical Investigation of Electric and Magnetic Properties of Benzene-Vanadium Sandwich Complex Chain. The Japan Society of Applied Physics, 44, 7954-7956.
<br>https://doi.org/10.1143/JJAP.44.7954Zhang, Z., Wu, X., Guo, W. and Zeng, X.C. (2010) Carrier-Tunable Magnetic Ordering in Vanadium-Naphthalene Sandwich Nanowires. Journal of the American Chemical Society, 132, 10215-10217.
<br>https://doi.org/10.1021/ja1029057Zhang, T., Zhu, L., Wu, Q., Yang, S.W. and Wang, J. (2012) Structures and Magnetism of Multinuclear Vanadium- Pentacene Sandwich Clusters and Their 1D Molecular Wires. The Journal of Chemical Physics, 137, Article ID: 164 309. <br>https://doi.org/10.1063/1.4759505Shen, L., Yang, S.W., Ng, M.F., Ligatchev, V., Zhou, L. and Feng, Y. (2008) Charge-Transfer-Based Mechanism for Half-Metallicity and Ferro-magnetism in One-Dimensional Organometallic Sandwich Molecular Wires. Journal of the American Chemical Society, 130, 13956-13960. <br>https://doi.org/10.1021/ja804053aLiu, W., Dolg, M. and Fulde, P. (1998) Calculated Properties of Lanthanocene Anions and the Unusual Electronic Structure of Their Neutral Counterparts. Inorganic Chemistry, 37, 1067-1072. <br>https://doi.org/10.1021/ic9704703Zhang, X. and Wang, J. (2010) Ab Initio Study of Bond Characteristics and Magnetic Properties of Mixed-Sandwich V<sub>n</sub>Bz<sub>m</sub>Cp<sub>k</sub> Clusters. The Journal of Physical Chemistry A, 114, 2319-2323. <br>https://doi.org/10.1021/jp907834vChaquin, P., Costa, D., Lepetit, C. and Che, M. (2001) Structure and Bonding in a Series of Neutral and Cationic Transition Metal-Benzene η<sup>6</sup> Complexes [M(η<sup>6</sup>-C<sub>6</sub>H<sub>6</sub>)]<sup>n+</sup> (M = Ti, V, Cr, Fe, Co, Ni, and Cu). Correlation of Charge Transfer with the Bathochromic Shift of the E<sub>1</sub> Ring Vibration. The Journal of Physical Chemistry A, 105, 4541-4545.
<br>https://doi.org/10.1021/jp004278pMurahashi, T., Fujimoto, M., Oka, M., Hashimoto, Y., Uemura, T., Tatsu-mi, Y., Nakao, Y., Ikeda, A., Sakaki, S. and Kurosawa, H. (2006) Discrete Sandwich Compounds of Monolayer Palla-dium Sheets. Science, 313, 1104-1107.
<br>https://doi.org/10.1126/science.1125245Xiang, H., Yang, J., Hou, J.G. and Zhu, Q. (2006) One-Dimensional Transition Metal-Benzene Sandwich Polymers: Possible Ideal Conductors for Spin Transport. Journal of the American Chemical Society, 128, 2310-2314.Kua, J. and Tomlin, K.M. (2006) Computational Study of Multiple-Decker Sandwich and Rice-Ball Structures of Neutral Titanium-Benzene Clusters. The Journal of Physical Chemistry A, 43, 11988-11994.
<br>https://doi.org/10.1021/jp065341zZhang, X., Ng, M.F., Wang, Y., Wang, J. and Yang, S.W. (2009) Theoret-ical Studies on Structural, Magnetic, and Spintronic Characteristics of Sandwiched Eu<sub>n</sub>COT<sub>n+1</sub> (n = 1-4) Clusters. ACS Nano, 3, 2515-2522.
<br>https://doi.org/10.1021/nn900401bZhu, S., Fu, H., Gao, G., Wang, S., Ni, Y. and Yao, K. (2013) A First Principles Study of Novel One-Dimensional Organic Half-Metal Vanadium-Cyclooctatetraene Wire. The Journal of Chemical Physics, 139, Article ID: 024309.
<br>https://doi.org/10.1063/1.4813406Miyajima, K., Nakajima, A., Yabushita, S., Knickelbein, M.B. and Kaya, K. (2004) Ferromagnetism in One-Dimen- sional Vanadium-Benzene Sandwich Clusters. Journal of the American Chemical Society, 126, 13202-13203.
<br>https://doi.org/10.1021/ja046151+Wang, J.L. and Jellinek, J. (2005) Infrared Spectra of V<sub>n</sub>Bz<sub>n+1</sub> Sandwich Clusters: A Theoretical Study of Size Evolution. The Journal of Physical Chemistry A, 109, 10180-10182. <br>https://doi.org/10.1021/jp055532mYao, X., Zhang, X. and Wang, J. (2014) The Bonding Characteristics, Electronic and Magnetic Properties of Organometallic Sandwich Clusters and Nanowires. International Journal of Quantum Chemistry, 115, 607-617.
<br>https://doi.org/10.1002/qua.24843Zhang, X., Wang, J. and Zeng, X.C. (2009) Ab Initio Study of Structural, Electronic, and Magnetic Properties of V<sub>n</sub>(C60)<sub>m</sub> Complexes. The Journal of Physical Chemistry A, 113, 5406-5413. <br>https://doi.org/10.1021/jp8064272Nagao, S., Kurikawa, T., Miyajima, K., Nakajima, A. and Kaya, K. (1998) Formation and Structures of Transition Metal-C60 Clusters. The Journal of Physical Chemistry A, 102, 4495-4500. <br>https://doi.org/10.1021/jp981136aPerdew, J. P., Burke, K. and Ernzerhof, M. (1997) Generalized Gradient Approximation Made Simple. Physical Review Letters, 77, 3865-3868. <br>https://doi.org/10.1103/PhysRevLett.77.3865Wang, J., Acioli, P.H. and Jellinek, J. (2005) Structure and Magnetism of V<sub>n</sub>Bz<sub>n+1</sub> Sandwich Clusters. Journal of the American Chemical Society, 127, 2812-2813. <br>https://doi.org/10.1021/ja043807qMiyajima, K., Knickelbein, M.B. and Nakajima, A. (2005) Magnetic Properties of Lanthanide Organometallic Sandwich Complexes Produced in a Molecular Beam. Polyhedron, 24, 2341-2345.
<br>https://doi.org/10.1016/j.poly.2005.03.175Miyajima, K., Knickelbein, M.B. and Nakajima, A. (2008) Stern-Gerlach Study of Multidecker Lanthanide-Cyclooctatetraene Sandwich Clusters. The Journal of Physical Chemistry A, 112, 366-375.
<br>https://doi.org/10.1021/jp0766196