Structures and stabilities of CaC3 isomers

Largo, Antonio; Barrientos, Carmen; Ziurys, L. M.

doi:10.1016/s0009-2614(02)00284-1

Cited by 9 publications

(7 citation statements)

References 32 publications

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“…The effect of employing high-level theoretical methods and extension of the basis set on the results of this type of compounds have been analyzed in our previous studies on CaC 2 24 and CaC 3 25 systems. In general, a good agreement between the results obtained with the B3LYP/6-311G(d) level and other more expensive theoretical methods is observed.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Barrientos

Largo

2004

J. Phys. Chem. A

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CaC n , CaC n +, and CaC n - (n = 1−8) monocyclic clusters have been studied using the B3LYP density functional method. Predictions for several molecular properties that could help in possible experimental characterization, such as equilibrium geometries, electronic structures, dipole moments, and vibrational frequencies, have been reported. For the CaC n monocyclic clusters, the electronic ground state is found to be a singlet for n-even clusters, whereas in the case of n-odd, singlet and triplet states are predicted to lie very close in energy. Both anionic and cationic clusters have doublet ground states, with the only exception of CaC3 + that has a 4B1 ground state. An even−odd parity effect, with n-even clusters being more stable than n-odd ones, is found for both neutral and anionic species, whereas in the case of cationic species this effect is slight and reversed. Ionization potentials exhibit also a clear parity alternation trend, with n-even clusters having larger values than n-odd ones. In the case of the electron affinities, a slight variation is found. It is also predicted that all neutral clusters prefer cyclic arrangements, with cyclic isomers being more favored for n-even clusters. Monocyclic ground states are also predicted for the first members of the series in the case of anionic and cationic monocyclic clusters.

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Section: Methodsmentioning

confidence: 99%

Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Barrientos

Largo

2004

J. Phys. Chem. A

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“…The CaC molecule is of great importance in metal carbide astrophysics, , since on the basis of its natural abundance it became a strong candidate to be detected in space, and therefore it has received some attention from both theoretical − and experimental investigations. , In the past few years, we have carried out theoretical studies on both CaC 2 and CaC 3 systems in order to provide predictions of their molecular parameters that could help in their eventual experimental observation. In addition, we have also performed a theoretical study on the MgC n /MgC n + /MgC n - systems. , Calcium is isovalent with magnesium and to our knowledge no published works exist for larger CaC n clusters.…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of the Open-Chain Calcium-Doped Carbon Clusters CaC_n, CaC_n⁺, and CaC_n^- (n = 1−8)

Largo

Barrientos

2004

J. Phys. Chem. A

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A DFT theoretical study of the CaC n, CaC n + , CaC n -(n ) 1-8) open-chain clusters has been carried out using the B3LYP method with both 6-311G(d) and 6-311+G(d) basis sets. For each species several molecular properties such as vibrational frequencies, dipole moments, and rotational constants are reported. For the CaC n open-chain clusters the lowest-lying states correspond to triplet states for n-odd members, whereas in the n-even species the ground states were found to be singlets. Cationic clusters have doublet ground states with the exception of the smallest one, CaC + . In CaC nclusters, except for CaC 3 -, the ground state is alternate between quartets (for n-odd members) and doublets (for n-even members). The incremental binding energy diagrams show a clear odd-even alternation in the cluster stability in both neutral and anionic clusters with their n-even members being more stable than the corresponding n-odd ones, while the parity effects is less pronounced for the cationic clusters. This odd-even alternation was also found for the electron affinities, whereas there is not a clear alternation in the ionization potentials.

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“…One of the reasons for this interest is that several binary compounds of general formula C n X, especially containing sulfur, silicon, and phosphorus, have been detected in space. − Since other small binary compounds containing metallic elements could be interesting in astrochemistry, much effort has been devoted to the theoretical prediction of structural properties of such molecules in order to aid in their identification in astronomical sources. This is the case of small metal carbides such as AlC 3 , MgC 3 , NaC 3 , and CaC 3 , which have recently been the subject of theoretical studies. − …”

Section: Introductionmentioning

confidence: 99%

Structure and Stability of Small NaC_n, NaC_n⁺, and NaC_n^- Clusters: A Theoretical Study

2003

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NaC n , NaC n + , and NaC n -(n ) 1-8) open-chain and cyclic clusters have been studied using the B3LYP method. Predictions for several molecular properties that could help in possible experimental characterization, such as equilibrium geometries, electronic energies, dipole moments, and vibrational frequencies, are provided. NaC n open-chain clusters are predicted to be linear with 2 Π lowest-lying states, whereas for both cationic and anionic clusters the lowest-lying state alternates between singlet and triplet. Also, cyclic neutral clusters have doublet lowest-lying states. An even-odd alternation in stability is observed for both cationic and anionic cyclic clusters, whereas no parity effect is observed generally for the corresponding neutrals. Ionization potentials and electron affinities of NaC n cyclic clusters also exhibit a clear even-odd parity effect. It is generally observed that removing an electron destabilizes the cyclic isomer, whereas adding an electron generally increases the stability of the cyclic species. NaC 2 and NaC 3 are predicted to have cyclic ground states, whereas most anionic clusters up to n ) 8 prefer also a cyclic arrangement.

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Structures and stabilities of CaC3 isomers

Cited by 9 publications

References 32 publications

Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Structure and Properties of the Open-Chain Calcium-Doped Carbon Clusters CaC_n, CaC_n⁺, and CaC_n^- (n = 1−8)

Structure and Stability of Small NaC_n, NaC_n⁺, and NaC_n^- Clusters: A Theoretical Study

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Structures and stabilities of CaC3 isomers

Cited by 9 publications

References 32 publications

Theoretical Study of the Structures and Stabilities of Small CaCn, CaCn+, and CaCn-(n= 1−8) Cyclic Clusters

Theoretical Study of the Structures and Stabilities of Small CaCn, CaCn+, and CaCn-(n= 1−8) Cyclic Clusters

Structure and Properties of the Open-Chain Calcium-Doped Carbon Clusters CaCn, CaCn+, and CaCn- (n = 1−8)

Structure and Stability of Small NaCn, NaCn+, and NaCn- Clusters: A Theoretical Study

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Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Theoretical Study of the Structures and Stabilities of Small CaC_n, CaC_n⁺, and CaC_n^-(n= 1−8) Cyclic Clusters

Structure and Properties of the Open-Chain Calcium-Doped Carbon Clusters CaC_n, CaC_n⁺, and CaC_n^- (n = 1−8)

Structure and Stability of Small NaC_n, NaC_n⁺, and NaC_n^- Clusters: A Theoretical Study