A theoretical study on the clusters Irn with n = 4, 6, 8, 10

Feng, Jian-Nan; Huang, Xuri; Li, Ze-Sheng

doi:10.1016/s0009-2614(97)00840-3

Cited by 19 publications

(22 citation statements)

References 10 publications

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“…We have seen that the tetrahedral structure is the most stable structure in agreement with this experimental result and theoretical study which obtained tetrahedron having bond length of 2.79 Å (Feng et al 1997). For the alloyed tetramers also, the tetrahedron structure came out to be the most stable of all the configurations studied.…”

Section: Resultssupporting

confidence: 89%

“…The predicted stable geometries in theoretical studies include tetrahedral (Feng et al 1997), a butterfly structure (Bussai et al 2005), rhombus (Pawluk et al 2005), and square (Stevanovic et al 2012) whereas experiments has showed tetrahedral as the most stable structure having a bond length of 2.71 Å (Deutsch et al 1997). We have seen that the tetrahedral structure is the most stable structure in agreement with this experimental result and theoretical study which obtained tetrahedron having bond length of 2.79 Å (Feng et al 1997).…”

Section: Resultssupporting

confidence: 84%

“…Studies have shown that there exists a low translational energy pathway for the dissociation of methane using Ir as the catalyst (Reeves et al 2001). Iridium clusters of various sizes are being studied both experimentally (Watzky and Finke 1997;Wang and Ehrlich 1997) and theoretically (Feng et al 1997;Bussai et al 2005;Pawluk et al 2005;Stevanovic et al 2012). Feng et al (1997) investigated the reactivity of Ir clusters from 4 to 10 atoms.…”

Section: Introductionmentioning

confidence: 99%

“…Iridium clusters of various sizes are being studied both experimentally (Watzky and Finke 1997;Wang and Ehrlich 1997) and theoretically (Feng et al 1997;Bussai et al 2005;Pawluk et al 2005;Stevanovic et al 2012). Feng et al (1997) investigated the reactivity of Ir clusters from 4 to 10 atoms. Another study on Ir clusters supported on Ir (111) substrate showed that the shape and size affects the stability and higher stabilities are achieved for larger clusters containing 19 and 39 atoms (Wang and Ehrlich 1997).…”

Section: Introductionmentioning

confidence: 99%

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First principles studies of Fe m Ir n (2 ≤ m + n ≤ 4) nano clusters

Aravindh

2013

Appl Nanosci

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The structure, binding energy, magnetic moments, and electronic structure of Fe m Ir n (2 B m ? n B 4) nano clusters are investigated using first principles density functional theory techniques. Fully unconstrained structural relaxations are undertaken by considering all possible non-equivalent cluster structures. The optimized clusters are all compact, indicating a clear tendency to maximize the number of nearest neighbor Fe-Ir pairs. The binding energy shows an increment with cluster size. All the clusters preserve ferromagnetic order after optimization and the average magnetic moment shows a general increment with Fe concentration. An enhancement of the local Fe moments in Ir-rich environment is observed, while that of Ir is minimal. The highest occupied molecular orbitallowest unoccupied molecular orbital energy gaps show a general reduction with alloying, indicating more metallicity for the doped clusters than the pure ones.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First principles studies of Fe m Ir n (2 ≤ m + n ≤ 4) nano clusters

Aravindh

2013

Appl Nanosci

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“…Two density functional theory (DFT) studies on bare Ir n clusters for n = 4, 6, 8, 10 [64] and n = 2-15 [65] have been published. Both studies find singlet Ir 4 to be a tetrahedron, while singlet Ir 6 is a prism.…”

Section: Catalyst Modelsmentioning

confidence: 99%

The Decomposition of Hydrazine in the Gas Phase and over an Iridium Catalyst

Schmidt

Gordon

2013

Zeitschrift Für Physikalische Chemie

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Hydrazine / Gas Phase / Ir Catalyst / Quantum ChemistryHydrazine is an important rocket fuel, used as both a monopropellant and a bipropellant. This paper presents theoretical results to complement the extensive experimental studies of the gas phase and Ir catalyzed decompositions involved in the monopropellant applications of hydrazine. Gas phase electronic structure theory calculations that include electron correlation predict that numerous molecular and free radical reactions occur within the same energy range as the basic free radical pathways: NN bond breaking around 65 kcal/mol and NH bond breaking around 81 kcal/mol. The data suggest that a revision to existing kinetics modeling is desirable, based on the energetics and the new elementary steps reported herein. A supported Ir 6 octahedron model for the Shell 405 Iridium catalyst used in thrusters was developed. Self-Consistent Field and electron correlation calculations (with core potentials and associated basis sets) find a rich chemistry for hydrazine on this catalyst model. The model catalyst provides dramatically lower NN and NH bond cleavage energies and an even smaller barrier to breaking the NH bond by NH 2 abstractions. Thus, the low temperature decomposition over the catalyst is interpreted in terms of consecutive NH 2 abstractions to produce ammonia and nitrogen. The higher temperature channel, which has hydrogen and nitrogen products, may be due to a mixture of two mechanisms. These two mechanisms are successive NH cleavages with surface H + H recombinations, and the same type of assisted H 2 eliminations found to occur in the gas phase part of this study.

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