Global Minimum Structure Research Articles

Density functional theory study of ZnnInn (n = 2–10) alloy clusters

The geometrical structure, mean square displacement and electronic properties of ZnnInn(n = 2–10) alloy clusters have been systematically studied by means of density functional theory. The stability of zinc-indium clusters has been discussed. Ab-initio molecular dynamics were performed to exhaust search the global minimum structures of the clusters on the level of GGA-PBE by DMol3 package, Then, the structures were optimized and further calculated the mean square displacement, HOMO-LUMO gap and NBO on the level of B3LYP/LANL2DZ by using Gaussian program.The results show that as the size increases, the structure tends to be spherical, In atoms and Zn atoms are dispersed in the system, The binding force of In-In bond and Zn-In bond is stronger than that of Zn-Zn bond. Combined with our calculated results, it is found that with the increase of cluster size, the non-metallicity of clusters decreases while the metallicity of clusters increases, and even clusters are more stable than odd clusters. The interaction between zinc and indium can be analyzed at the atomic level to provide ideas for the separation and recovery of indium from zinc and indium in practical experiments.

Atomic Clusters: Structure, Reactivity, Bonding, and Dynamics.

Atomic clusters lie somewhere in between isolated atoms and extended solids with distinctly different reactivity patterns. They are known to be useful as catalysts facilitating several reactions of industrial importance. Various machine learning based techniques have been adopted in generating their global minimum energy structures. Bond-stretch isomerism, aromatic stabilization, Rener-Teller effect, improved superhalogen/superalkali properties, and electride characteristics are some of the hallmarks of these clusters. Different all-metal and nonmetal clusters exhibit a variety of aromatic characteristics. Some of these clusters are dynamically stable as exemplified through their fluxional behavior. Several of these cluster cavitands are found to be agents for effective confinement. The confined media cause drastic changes in bonding, reactivity, and other properties, for example, bonding between two noble gas atoms, and remarkable acceleration in the rate of a chemical reaction under confinement. They have potential to be good hydrogen storage materials and also to activate small molecules for various purposes. Many atomic clusters show exceptional opto-electronic, magnetic, and nonlinear optical properties. In this Review article, we intend to highlight all these aspects.

An investigation on the structures of Sc2B8 clusters by a combination of the genetic algorithm and density functional theory (GA-DFT) and its CO-adsorption

The structures of Sc2B8 were investigated by a combination of genetic algorithm (GA) with PBE functional (GA-DFT). Its CO-adsorption were studied by calculations with PBE functional. Many structures include local minimum and global minimum structures were determined. The structural parameters, relative energy, energetic properties, dissociation energy were reported. Results indicated that CO molecule can be adsorbed at many positions of these clusters. Scandium doped boron cluster can be used to produce materials that can treat CO gas by adsorption method.

Search for Global Minimum Structures of (n = 1-15) Using xTB-Based Basin-Hopping Algorithm.

A new program for searching global minimum structures of atomic clusters using basin-hopping algorithm based on the xTB method was developed here. The program can be performed with a much higher speed than its replacement directly based on DFT methods. Considering the structural varieties and complexities in finding their global minimum structures, phosphorus cluster cations were studied by the program. The global minimum structures of cationic (n = 1–15) clusters are determined through the unbiased structure searching method. In the last step, further DFT optimization was performed for the selected isomers. For (n = 1–4, 7), the found global minimum structures are in consistent with the ones previously reported; while for (n = 5, 6, 8–12), newly found isomers are more energy-favorable than those previously reported. And those for (n = 13–15) are reported here for the first time. Among them, the most stable isomers of (n = 4–6, 9) are characterized by their C3v, Cs, C2v and Cs symmetry, in turn. But those of (n = 7, 8, 10–12), no symmetry has been identified. The most stable isomers of and are characterized by single P-P bonds bridging units inside the clusters. Further analysis shows that the pnicogen bonds play an important role in the stabilization of these clusters. These results show that the new developed program is effective and robust in searching global minimum structures for atom clusters, and it also provides new insights into the role of pnicogen bonds in phosphorus clusters.

Unravelling the diarsenic hydrides: Reactivity and spectroscopic properties

Diarsenic hydrides in the ground state are among the simplest molecular systems, with an arsenic-arsenic bond. This investigation aimed to characterize the structural and electronic properties of diarsenic hydrides, as well as the relative stability between their isomers. The As2Hn (n=1-4) structures are represented by hydrogen diarsenide (As2H), the equilibrium structures of diarsene isomers (As2H2), a trihydride diarsenic species (diarsenium, As2H3), and the diarsine molecule (H2AsAsH2) and its ylide isomer (H3AsAsH). The energetic profile calculated at the CCSD(T)/CBS level indicated trans-HAsAsH as the global minimum structure among the dihydrides, and diarsine as the most stable configuration among the tetrahydrides, lying 33 kcal mol−1 below H3AsAsH. The diarsenic bonds were characterized with σ (2.362−2.490 Å) and π (2.177-2.268 Å) bond characters corroborated by natural bond orbital (NBO) and bond order index analyses. The accuracy to reproduce the experimental data was also evaluated at the DFT and MP2 levels using a training set of 8 arsenic-bearing molecules. The results showed that B97D functional showed the best performance in reproducing observable frequencies with slight differences among cc-pVnZ and aug-cc-pVnZ basis sets (n=D, T). On the other hand, B2PLYP/aug-cc-pVTZ achieve the best agreement with experimental results by using vibrational second-order perturbation theory (VPT2) to rationalize the vibrational results.

Growth of rare gases on coronene

We study the growth of rare gases (Rg) Ne, Ar and Kr on coronene (Cor) molecules, Cor-(Rg)\(_N\). The study is taken up to sizes N=60, and we show the global energy minima for those clusters. Improved Lennard-Jones and atom-bond potentials are used to represent the Rg-Rg and Rg-Cor interactions, respectively. The Basin-Hopping (BH) global optimization technique is employed to locate the putative global energy minimum structures. Results are presented for Cor-(Ne), Cor-(Ar) and Cor-(Kr) systems. Both classical Cor-(Ar)\(_N\) and Cor-(Kr)\(_N\) clusters present the same “magic numbers” for N=3, 6, 10, 14, 19 and 38. This last number marks the first layer of solvation. For Cor-(Ne)\(_N\) clusters, we consider quantum effects adding the zero-point energy (ZPE) into the classical potential energy minima (BH-ZPE). This semiclassical approximation is compared with quantum diffusion Monte Carlo (DMC) calculations up to N=20, obtaining a good agreement and showing that this approximation works reasonably well. In this BH-ZPE approach, high stability configurations for Cor-(Ne)\(_N\) clusters are obtained at N=6, 14, 42, 51 and 57. However, we have not found any evidence of a first solvation layer using either the semiclassical BH-ZPE or the classical BH one.

A joint experimental and theoretical study on structural, electronic, and magnetic properties of MnGen - (n = 3-14) clusters.

A systematic structure and property investigation of MnGen - (n = 3-14) was conducted by means of density functional theory coupled with mass-selected anion photoelectron spectroscopy. This combined theoretical and experimental study allows global minimum and coexistence structures to be identified. It is found that the pentagonal bipyramid shape is the basic framework for the nascent growth process of MnGen - (n = 3-10), and from n = 10, the endohedral structures can be found. For n = 12, the anion MnGe12 - cluster probably includes two isomers: a major isomer with a puckered hexagonal prism geometry and a minor isomer with a distorted icosahedron geometry. Specifically, the puckered hexagonal prism isomer follows the Wade-Mingos rules and can be suggested as a new kind of superatom with the magnetic property. Furthermore, the results of adaptive natural density partitioning and deformation density analyses suggest a polar covalent interaction between Ge and Mn for endohedral clusters of MnGe12 -. The spin density and natural population analysis indicate that MnGen - clusters have high magnetic moments localized on Mn. The density of states diagram visually shows the significant spin polarization for endohedral structures and reveals the weak interaction between the Ge 4p orbital and the 4s, 3d orbitals of Mn.

Structural and electronic properties of medium-sized beryllium doped magnesium BeMgn clusters and their anions

Bimetallic clusters have attracted much attention because of the structural and property changes that occur: cluster size and doping. Here, we performed a structural search of the global minimum for bimetallic BeMgn0/− (n = 10–20) clusters by utilizing efficient CALYPSO structural searching program with subsequent DFT calculations. A large number of low energetic isomers converge and the most stable structures are confirmed by comparing the total energies for different cluster sizes. Satisfactory agreement between theoretical and experimental PES spectra demonstrates the validity of our predicted global minimum structures. It is found that the most stable structures of BeMgn0/− clusters are filled cage-like frameworks at n = 10–20. The localized position of Be atoms changes from completely encapsulated sites to surface sites, after which the position reverts to the caged Mg motif. In all BeMgn0/− clusters, the charge transfers from the Mgn motif to Be atoms. Increasing occupations of p orbitals manifest their increasing metallic behaviors. A stability analysis revealed that the D4d symmetric BeMg16 caged structure with one centred Be atom has robust stability, which can be because BeMg16 possesses a closed electronic shell of 1S21P61D101F42S21F10 filled with 34 valence electrons and strong Be-Mg bonds due to s-p hybridization. This finding is supported by multi-centre bonds and Mayer bond order analyses.

Theoretical study on the structural evolution and hydrogen storage in NbHn (n = 2–15) clusters

Niobium hydrides are attractive superconductors. Exploring the formation process of niobium hydrides is essential to elucidate the mechanism of superconductivity. One of the key issues is to clarify the atomic stacking patterns of Nb and H atoms, i.e., the structural evolution of Nb–H clusters. Here, the low-energy structural isomers of NbHn (n = 2–15) clusters are determined using the CALYPSO method combined with density functional theory calculations. Geometries were fully optimized at the B3LYP/LANL2DZ/6–311++G(d) level of theory to determine global minimum structures for each size. The results indicate that NbH13 is the most stable cluster in this size range. The 4d atomic orbital of Nb and the hydrogen 1s atomic orbital participate largely to the internal binding of the NbH13 cluster. They hydrogen storage density and adsorption energy of this cluster are calculated to be 12.4 wt% and 2.58 eV, respectively. The high hydrogen storage density, suitable hydrogen adsorption energy, and high stability of NbH13 shows promise as a hydrogen storage material. These results provide fundamental information for further design of metal hydrogen storage materials.

How O2-Binding Affects Structural Evolution of Medium Even-Sized Gold Clusters Aun- (n = 20-34).

We report the first joint anion photoelectron spectroscopy and theoretical study on how O2-binding affects the structures of medium even-sized gold clusters, Aun- (n = 20-34), a special size region that entails a variety of distinct structures. Under the temperature conditions in the current photoelectron spectroscopy experiment, O2-bound gold clusters were observed only for n = 22-24 and 34. Nevertheless, O2 binding with the clusters in the size range of n = 20-34 can be still predicted based on the obtained global-minimum structures. Consequently, a series of structural transitions, from the pyramidal to fused-planar to core-shell structures, are either identified or predicted for the AunO2- clusters, where the O2-binding is in either superoxo or peroxo fashion. The identified global-minimum structures of AunO2- (n = 20-34) also allow us to gain improved understanding of why the clusters Aun- (n = 26-32) are less reactive with O2 in comparison to others.

Catalytic properties of nano-brass clusters: A density functional theory study

Brass (Cu-Zn) alloys are widely used as industrial materials. The structural and electronic properties of Cu-Zn clusters have been reported in theory recently [(Liu and Cheng, 2019); Journal of Cluster Science 2020, 31, 601–607], and the works have attracted intense research interest both experimentally and theoretically. However, to our knowledge the catalytic properties of the Cu-Zn clusters have not been analyzed. Here, we carry out our explorations of the catalytic properties of the selected Cu-Zn superatoms related to their geometric structures and stability. First, the global minimum structures of CuxZny (x + y = 14) alloy clusters are searched by an unbiased global method of genetic algorithm directly using the DFT functional. Among them, the spherical Cu8Zn6 and Cu10Zn4 satisfy magic numbers of the Jellium model and are two stable metal superatoms in this cluster series. Then, electrostatic potential surfaces of the brass clusters are analyzed, and the calculated results show that such alloy superatom has remarkable σ-holes with positive potential regions. Moreover, these electron-deficient regions can be considered as interaction sites with some Lewis bases. When a Lewis base CO gas molecule is attached to the alloy superatoms, we found that the CO bond distance become slightly elongated and its stretching frequency presents a significant red-shift. This is because that delocalized electrons of brass superatoms transfer towards the anti-bond π orbitals of CO molecule. Hence, these clusters may serve as potential catalysts for the covalent bond activation. However, the NH bond lengths of the clusters upon the NH3 adsorption are in accordance with that of the free NH3, and the analysis shows that the classical metals bind the NH3 molecule via donor interactions.

Expanded Inverse-Sandwich Complexes of Lanthanum Borides: La2B10- and La2B11.

Inverse-sandwich structures have been observed recently for dilanthanide boride clusters, in which two Ln atoms sandwich a monocyclic Bx ring for x = 7-9. An interesting question is if larger Bx rings are possible to form such inverse-sandwich clusters. Here we address this question by investigating La2B10- and La2B11- using photoelectron spectroscopy and ab initio quantum chemical calculations. Photoelectron spectra of La2B10- and La2B11- show complicated, but well-resolved, spectral features that are used to compare with theoretical calculations. We have found that global minimum structures of the two clusters are based on the octa-boron ring. The global minimum of La2B10- consists of two chiral enantiomers with C1 symmetry, which can be viewed as adding a B2 unit off-plane to the B8 ring, whereas that of La2B11- can be viewed as adding a B3 unit in-plane to the B8 ring in a second coordination shell. Chemical bonding analyses reveal localized B-B bonds on the edge of the clusters and delocalized bonds in the expanded boron frameworks. The interactions between the La atoms and the boron frameworks include the unique (d-p)δ bonding, which was found to be the key for inverse-sandwich complexes with monocyclic boron rings. The current study confirms that the largest monocyclic boron ring to form the inverse-sandwich structures is B9 and provide insights into the structural evolutions of larger lanthanide boride clusters.

The Triple Salt 2(C7H9N4O2)[MoOCl4(H2O)] ⋅ 2(C7H9N4O2)Cl ⋅ (H17O8)Cl Containing a C2‐symmetrical Unbranched H+(H2O)8Zundel type Species in a Framework Composed of Theophyllinium, Aquatetrachloridooxidomolybdate and Chloride Ions

AbstractFrom a concentrated hydrochloric acid solution of molybdenum‐(V) chloride and theophylline octaaquahydrogen(1+) tetrakis(theophyllinium) bis[aquatetrachloridooxidomolybdate(1−)] tri‐chloride, C7H9N4O2)4(H17O8)[MoOCl4(H2O)]2Cl3, (1) was obtained. The light emerald green inorganic‐organic hybrid material can be rationalized as a triple salt according to the formula 2(C7H9N4O2)[MoOCl4(H2O)] ⋅ 2(C7H9N4O2)Cl ⋅ (H17O8)Cl. The ions involved are connected by charge‐supported hydrogen bonds to form a 3D framework. The unique H17O8+ moiety features a chain of eight hydrogen bonded water molecules, with the excess proton defining a H5O2+ Zundel‐ion (O⋅⋅⋅O distance 240.3(6) pm) in the middle of the chain, and is placed with crystallographic site symmetry 2. Although engaged in strong O−H⋅⋅⋅O bonding to the neighboring water molecules in the chain (O⋅⋅⋅O distance 262.9(4) pm) and in hydrogen bonding to a carbonyl group of a theophyllinium ion, both the conformation of the H5O2+ unit and the geometry of the very strong central O−H−O bond fit to the C2‐symmetrical global minimum structure of an isolated H5O2+ species. The outer water molecules of the H17O8+ moiety are further engaged in N−H⋅⋅⋅O, O−H⋅⋅⋅Cl and O−H⋅⋅⋅O=C bonds.

Unravelling the Origin of the Linear Structures Distortions of the Acetylene Isoelectronic Compounds (Disilyne, Digermyne, and Distannyne)

The role and contributions of the effective factors on the structural properties of acetylene (1), disilyne (2), digermyne (3), and distannyne (4) were examined by means of LC-ωPBE long-range corrected density functional method with TZP basis set on all atoms. Although the ground state structure of acetylene (1) is linear (D∞h-symmetry), the trans-bent (C2h, as a local minimum) and di-bridged structures (C2v, as a global minimum) were found for compounds 2–4. Plotted electronic energies of the ground and excited states versus the nuclear displacement (by considering the symmetries of the normal modes) revealed that the negative curvatures of the ground state electronic configurations and the positive curvatures of the excited states of the adiabatic potential energy surfaces (APESs) result from mixing of the ground $$^{1}\Sigma _{{\text{g}}}^{ + }$$ and excited 1Πg states, revealing the presence of the strong pseudo Jahn–Teller effect (i.e., PJT ( $$^{1}\Sigma _{{\text{g}}}^{ + }$$ + 1Πg) ⊗ πg problem). The weak PJTE in acetylene (1) does not distort its linear configurations. The distortions of the linear (D∞h) configurations of compounds 2–4 to their corresponding trans-bent structures (C2h) are due to the PJTE associated with the mixing of the ground $$^{1}\Sigma _{{\text{g}}}^{ + }$$ state and third excited Πg states through the mixing of their HOMOs(πu) with their corresponding LUMOs+2(σu) ([HOMO(πu)] + [LUMO+1(σu)]) in compound 2, the mixing of the ground $$^{1}\Sigma _{{\text{g}}}^{ + }$$ state and second excited Πg states ([HOMO(πu)] + [LUMO(σu)]) in compound 3 and the ground $$^{1}\Sigma _{{\text{g}}}^{ + }$$ state and second excited Πg states ([HOMO(πu)] – [LUMO+1(σu)]) in compound 4. The higher- and lower-lying $$^{1}\Sigma _{{\text{u}}}^{ - }$$ , $$^{1}\Sigma _{{\text{u}}}^{ - }$$ , 1Δu, and 1Πu states are not involved in the PJT interactions. The trans-bent local minimum structures could be converted to their corresponding global minimum structures (di-bridge, C2v) by passing from axial symmetrical (C2) transition state geometries. The energy gaps between reference states (∆) in the linear (D∞h) configurations decrease from disilyne (2) to distannyne (4) while the energy difference between the linear (D∞h) and trans-bent (C2h) configurations increases from compound 2 to 3 but decreases from compound to compound 4, revealing the determining impacts of their corresponding vibronic coupling constants (F) which may control their corresponding D∞h → C2h distortion PJT stabilization energies. Importantly, the variations of the M–M-bond length differences in the linear (D∞h) and trans-bent (C2h) structures of compounds 2–4, Δ(rM–M) D∞h–C2h, correlate well with their corresponding PJT-stabilization energies.

Structural and dynamical properties of Au-Pd bimetallic nanoalloys supported on MgO(001)

ABSTRACT In this study, structural and dynamical properties of Au-Pd bimetallic nanoalloys supported on MgO(001) surface were investigated. Bimetallic nanoalloys were defined with three different compositions that represents 1:1(50%–50%), 1:3(25%–75%) and 3:1(75%–25%). The putative global minimum structures of bimetallic Au-Pd nanoalloys adsorbed on MgO(001) were examined. It was obtained that Au and Pd nanoparticles exhibit a preference both (001) and (111) epitaxial grown on MgO(001) and Au-Pd bimetallic nanoalloys favour (001) epitaxy on MgO(001). The obtained lowest energy structures were used initially for melting simulations. The melting temperatures of AunPd3n nanoalloys were obtained generally higher than the melting temperatures of AunPdn and Au3nPdn nanoalloys. Highlights Structural and dynamical properties of Au-Pd bimetallic nanoalloys supported on MgO(001) surface were investigated. Au and Pd nanoclusters exhibit a preference both (001) and (111) epitaxial grown on MgO(001) and Au-Pd bimetallic nanoalloys favour (001) epitaxy on MgO(001). The melting temperatures of AunPd3n nanoalloys were obtained generally higher than the melting temperatures of AunPdn and Au3nPdn nanoalloys.

The Characteristics of Disulfide-Centered Hydrogen Bonds.

The disulfide-centered hydrogen bonds in the three different model systems of diethyl disulfide⋅⋅⋅H2 O/H2 CO/HCONH2 clusters were characterized by high-resolution Fourier transform microwave spectroscopy and quantum chemical computations. The global minimum energy structures for each cluster are experimentally observed and are characterized by one of the three different S-S⋅⋅⋅H-C/N/O disulfide-centered hydrogen bonds and two O⋅⋅⋅H-C hydrogen bonds. Non-covalent interaction and natural bond orbital analyses further confirm the experimental observations. The symmetry-adapted perturbation theory (SAPT) analysis reveals that electrostatic is dominant in diethyl disulfide⋅⋅⋅H2 O/HCONH2 clusters being consistent with normal hydrogen bonds, whilst dispersion takes over in diethyl disulfide⋅⋅⋅H2 CO cluster. Our study gives accurate structural parameters for the disulfide bond involved non-covalent clusters providing important benchmarking data for the theoretical evaluation of more complex systems.

The Characteristics of Disulfide‐Centered Hydrogen Bonds

AbstractThe disulfide‐centered hydrogen bonds in the three different model systems of diethyl disulfide⋅⋅⋅H2O/H2CO/HCONH2 clusters were characterized by high‐resolution Fourier transform microwave spectroscopy and quantum chemical computations. The global minimum energy structures for each cluster are experimentally observed and are characterized by one of the three different S−S⋅⋅⋅H−C/N/O disulfide‐centered hydrogen bonds and two O⋅⋅⋅H−C hydrogen bonds. Non‐covalent interaction and natural bond orbital analyses further confirm the experimental observations. The symmetry‐adapted perturbation theory (SAPT) analysis reveals that electrostatic is dominant in diethyl disulfide⋅⋅⋅H2O/HCONH2 clusters being consistent with normal hydrogen bonds, whilst dispersion takes over in diethyl disulfide⋅⋅⋅H2CO cluster. Our study gives accurate structural parameters for the disulfide bond involved non‐covalent clusters providing important benchmarking data for the theoretical evaluation of more complex systems.

Exploring pentavalent phosphorous bonding in phosphoryl chloride-halocarbon heterodimers at low temperatures and ab initio Computations

In this work, POCl 3 prototype was examined with competing hydrogen, halogen, tetrel and pnicogen (phosphorus) bonding partners under isolated conditions at low temperatures, which were supported by quantum chemical calculations. Computations on 1:1 heterodimer of POCl 3 -CH 2 Cl 2 indicated that the multiple competing interactions were found to co-exist in all the heterodimers. Of the eight possible POCl 3 -CH 2 Cl 2 dimers, the experimentally important global minimum structure (PDCM-I) has a strong hydrogen bonding interaction with co-operative pentavalent phosphorus bonding. If hydrogen bonding is hampered with chlorine substitutions in the interacting partner and as with illustrative POCl 3 -CCl 4 dimer model, phosphorus bonding seems to dominate with co-operative halogen bonding interaction in the experimentally relevant ground state geometry (PCTC-I). Experimental evidence for the formation of the PDCM-I and PCTC-I heterodimers were discerned in Ar and N 2 matrixes using infrared spectroscopy.

The energy landscapes of bidisperse particle assemblies on a sphere.

The interplay between crystalline ordering, curvature, and size dispersity make the packing of bidisperse mixtures of particles on a sphere a varied and complex phenomenon. These structures have functional significance in a broad range of systems, such as cellular organisation in spherical epithelia, catalytic activity in binary colloidosomes, and chemical activity in heterofullerenes. In this contribution, we elucidate the potential energy landscapes for systems of repulsive, bidisperse particles confined to the surface of a sphere. It is commonly asserted that particle size dispersity destroys ordered arrangements, leading to glassy landscapes. Surprisingly, across a range of compositions, we find highly ordered global minima. Moreover, a minority of small particles is able to passivate defects, stabilising bidisperse global minima relative to monodisperse systems. However, our landscape analysis also reveals that bidispersity introduces numerous defective, low-lying states that are expected to cause broken ergodicity in corresponding experimental and computational systems. Probing the global minimum structures further, particle segregation is energetically preferred at intermediate compositions, contrasting with the approximate icosahedral global packing at either end of the composition range. Finally, changing the composition has a dramatic effect on the heat capacity: systems with low-symmetry global minima have melting temperatures an order of magnitude lower than monodisperse or high-symmetry systems. This observation may provide a further example of the principle of maximum symmetry: higher symmetry global minima exhibit a larger energy separation from the minima that define the high-entropy phase-like region of configuration space, raising the transition temperature.

Photoelectron spectroscopy and theoretical study of AlnC5-/0 (n = 1-5) clusters: structural evolution, relative stability of star-like clusters, and planar tetracoordinate carbon structures.

The AlnC5- (n = 1-5) clusters were detected in the gas-phase and were investigated via mass-selected anion photoelectron spectroscopy. The structures of AlnC5-/0 (n = 1-5) were explored by theoretical calculations. It is found that the structures of AlC5-/0 and Al2C5-/0 are linear while those of Al3C5-/0, Al4C5-/0, and Al5C5-/0 are two-dimensional. The most stable structures of AlC5-/0 and Al2C5-/0 are linear with the Al atoms attached to the ends of C5 chain. The most stable structures of Al3C5-/0 can be viewed as three Al atoms interacting with a nonlinear C5 chain. The most stable structure of Al4C5- anion is a planar structure composed of a C2 unit, a C3 unit, and two Al2 units, while that of the neutral Al4C5 cluster has four Al atoms connected to different positions of a distorted C5 chain. The global minimum structures of Al5C5-/0 are planar structures composed of an Al4C quadrilateral, two C2 groups, and an Al atom connected to two C2 groups. Planar tetracoordinate carbon (ptC) has been identified in the structures of both anionic and neutral Al5C5. It is worth mentioning that the star-like structure of Al5C5- is slightly higher in energy than the ground state structure. The comparison of theoretical calculations with the experimental spectra indicates the star-like structure of Al5C5- may also appear in our experiments.