01941nas a2200241 4500008004100000022001400041245011400055210006900169260005700238300000900295490000800304520105600312653002401368653003601392653001101428653002401439653002101463100002101484700002201505700002601527700001601553856013001569 2014 eng d a1432-881X00aComputational investigation on the catalytic activity of Rh-6 and Rh4Ru2 clusters towards methanol activation0 aComputational investigation on the catalytic activity of Rh6 and a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcDEC a15970 v1343 a

Catalysis of molecular activation of small molecules through scission of strong chemical bonds is one of the major challenges faced by chemists. More specifically, activation of the strong C-H and O-H bonds of various alcohols, especially methanol, is one of the various important intermediate steps of key organic reactions. Our present work explores a suitable metal cluster catalyst towards methanol dissociation. In particular, we have examined the effect of ruthenium doping (Rh:Ru = 2:1) on the catalytic activity of Rh-6 cluster towards methanol dissociation. Density functional theory-based calculations illustrate two competitive pathways for methanol dissociation, which are via O-H and C-H bond breaking. Both the pathways are found to be energetically favourable in the presence of bimetallic and mono-metallic clusters. Importantly, energy barrier for O-H bond dissociation reduces considerably in doped cluster as compared to pure Rh-6 cluster and is smaller than the values reported for a number of other small metallic clusters.

10aBimetallic Clusters10aDensity Functional Theory (DFT)10aDoping10aMethanol Activation10aRhodium Clusters1 aGhatak, Kamalika1 aSengupta, Turbasu1 aKrishnamurty, Sailaja1 aPal, Sourav uhttps://library.ncl.res.in/content/computational-investigation-catalytic-activity-rh-6-and-rh4ru2-clusters-towards-methanol-002323nas a2200217 4500008004100000022001400041245007500055210006900130260006700199300001200266490000800278520158100286653001801867653002201885653001001907100002701917700002201944700001801966700001601984856010502000 2015 eng d a0020-760800aElectron attachment to DNA and RNA nucleobases: an EOMCC investigation0 aElectron attachment to DNA and RNA nucleobases an EOMCC investig a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcJUN a753-7640 v1153 a

We report a benchmark theoretical investigation of both vertical and adiabatic electron affinities of DNA and RNA nucleobases: adenine, guanine, cytosine, thymine, and uracil using equation of motion coupled cluster method. The vertical electron affinity (VEA) values of the first five states of the DNA and RNA nucleobases are computed. It is observed that the first electron attached state is energetically accessible in gas phase. Furthermore, an analysis of the natural orbitals exhibits that the first electron attached states of uracil and thymine are valence-bound in nature and undergo significant structural changes on attachment of an extra electron, which reflects in the deviation of the adiabatic electron affinity (AEA) than that of the vertical ones. Conversely, the first electron attached states of cytosine, adenine, and guanine are in the category of dipole-bound anions. Their structure, by and large, remain unaffected on attachment of an extra electron, which is evident from the observed small difference between the AEA and VEA values. VEA and AEA values of all the DNA and RNA nucleobases are found to be negative, which implies that the first electron attached states are not stable rather quasi bound. The results of all previous theoretical calculations are out of track and shows large deviation with respect to the experimentally measured values, whereas, our results are found to be in good agreement. Therefore, our computed values can be used as a reliable standard to calibrate new theoretical methods. (c) 2015 Wiley Periodicals, Inc.

10aDNA-RNA bases10aelectron affinity10aEOMCC1 aDutta, Achintya, Kumar1 aSengupta, Turbasu1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/electron-attachment-dna-and-rna-nucleobases-eomcc-investigation-001942nas a2200169 4500008004100000022001400041245006400055210006300119260011000182300001600292490000600308520131200314100002201626700001701648700001601665856009101681 2015 eng d a2040-336400aOxidative addition of the C-I bond on aluminum nanoclusters0 aOxidative addition of the CI bond on aluminum nanoclusters aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUN a12109-121250 v73 a

Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly sensitive to the geometrical shapes and electronic structures of the clusters rather than their size, imposing the fact that comprehensive studies on aluminum clusters can be beneficial for nanoscience and nanotechnology. To understand the possible reaction mechanism in detail, the reaction pathway is investigated with the ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulation and the Natural Bond Orbital (NBO) analysis. In short, our theoretical study highlights the thermodynamic and kinetic details of C-I bond dissociation on aluminum clusters for future endeavors in cluster chemistry.

1 aSengupta, Turbasu1 aDas, Susanta1 aPal, Sourav uhttps://library.ncl.res.in/content/oxidative-addition-c-i-bond-aluminum-nanoclusters-001855nas a2200241 4500008004100000022001400041245016200055210006900217260008100286300001100367490000700378520090300385653002701288653003301315653003001348100002001378700001801398700002201416700001601438700001801454700001601472856012501488 2015 eng d a0953-407500aRelativistic equation-of-motion coupled-cluster investigation of the trends of single and double ionization potentials in the He and Be isoelectronic systems0 aRelativistic equationofmotion coupledcluster investigation of th aTEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLANDbIOP PUBLISHING LTDcJUN a1150090 v483 a

We employ a four-component spinor relativistic equation-of-motion coupled-cluster (EOMCC) method within the single-and double-excitation approximation to calculate the single ionization potentials (IPs) and double ionization potentials (DIPs) of the He and Be isoelectronic sequences up to Ne. The obtained results are compared with the available results from the National Institute of Standards and Technology (NIST) database to test the performance of the EOMCC method. We also present intermediate results at different levels of approximations in the EOMCC framework to gain insight of the effect of electron correlation. Furthermore, we investigate the dependence of the IPs and DIPs of these ions on the ionic charge and observe that these follow parabolic trends. Similarities between the trends of IPs and DIPs in both the classes of considered systems are categorically demonstrated.

10acoupled-cluster method10adouble ionization potentials10aequation-of-motion theory1 aPathak, Himadri1 aSahoo, B., K.1 aSengupta, Turbasu1 aDas, B., P.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-investigation-trends-single-and-double-101519nas a2200181 4500008004100000022001400041245007600055210006900131260007100200300001400271490000800285520085200293100001701145700002201162700002701184700001601211856011001227 2016 eng d a1089-563900aElectron detachment and subsequent structural changes of water clusters0 aElectron detachment and subsequent structural changes of water c a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB a1065-10730 v1203 a

A cost-effective equation of motion coupled cluster method, EOMIP-CCSD(2), is used to investigate vertical and adiabatic ionization potential as well as ionization-induced structural changes of water clusters and compared with CCSD(T), CASPT2, and MP2 methods. The moderate N-5 scaling and low storage requirement yields EOMIP-CCSD (2) calculation feasible even for reasonably large molecules and clusters with accuracy comparable to CCSD(T) method at much cheaper computational cost. Our calculations shed light on the authenticity of EOMIP-CCSD(2) results and establish a reliable method to study of ionization energy of molecular clusters. We have further investigated the performance of several classes of DFT functionals for ionization energies of water clusters to benchmark the results and to get a reliable functionals for the same.

1 aDas, Susanta1 aSengupta, Turbasu1 aDutta, Achintya, Kumar1 aPal, Sourav uhttps://library.ncl.res.in/content/electron-detachment-and-subsequent-structural-changes-water-clusters-001904nas a2200157 4500008004100000022001400041245008800055210006900143260011000212300001600322490000700338520124700345100002201592700001601614856011601630 2016 eng d a1463-907600aRadical attached aluminum nanoclusters: an alternative way of cluster stabilization0 aRadical attached aluminum nanoclusters an alternative way of clu aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a21746-217590 v183 a

The stability and electronic structure of radical attached aluminum nanoclusters are investigated using density functional theory (DFT). A detailed investigation shows good correlation between the thermodynamic stability of radical attached clusters and the stability of the attached radical anions. All other calculated parameters like HOMO-LUMO gap and charge transfer are also found to be consistent with the observed thermodynamic stabilities of the complexes. Investigation of the electronic structure of radical attached complexes further shows the presence of jellium structures within the core similar to the ligated clusters. Comparison with available experimental and theoretical data also proves the validity of superatomic complex theory for the radical attached clusters as well. Based on the evaluated thermodynamic parameters, selected radical attached clusters are observed to be more thermodynamically stable in comparison with experimentally synthesized ligated clusters. Stabilization of small metal clusters is one of the greatest challenges in current cluster science and the present investigation confirms the fact that radical attached clusters can provide a viable alternative to ligated clusters in the future.

1 aSengupta, Turbasu1 aPal, Sourav uhttps://library.ncl.res.in/content/radical-attached-aluminum-nanoclusters-alternative-way-cluster-stabilization01784nas a2200169 4500008004100000022001400041245006500055210006400120260007100184300001600255490000800271520118700279100002201466700001701488700001601505856009301521 2016 eng d a1932-744700aTransition metal doped aluminum clusters: an account of spin0 aTransition metal doped aluminum clusters an account of spin a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY a10027-100400 v1203 a

The influence of spin on the properties of small sized transition metal doped aluminum clusters are investigated in the framework of density functional theory (DFT). Detailed analysis on minimum spin doped aluminum clusters has shown prominent indication of odd even oscillation in various calculated properties, supporting the presence of jellium shell structures within them. However, optimized high spin ground state counterparts, on the other hand, show rather smooth trends consistent with the properties of bulk materials. Resemblance to the bulk transition metals is further reflected in the gradual declining trends of heat of adsorption of CO2 molecule on cluster surface by sequentially changing the dopant atom from scandium to zinc. All the observations are also compared and found to be consistent with the earlier theoretical and experimental findings as obtained in the current literature. The similarities in the properties between atomic clusters and the bulk material is of utter importance and indeed precious considering the promising influence of the acquired information in understanding the process of evolution of nanoparticles from constituent atoms.

1 aSengupta, Turbasu1 aDas, Susanta1 aPal, Sourav uhttps://library.ncl.res.in/content/transition-metal-doped-aluminum-clusters-account-spin01880nas a2200157 4500008004100000245011500041210006900156260000800225300001600233490000800249520128700257100002201544700002001566700001601586856012001602 2017 eng d00aEffect of ligand attachment on the C-I bond dissociation process on aluminum nanoclusters: a DFT investigation0 aEffect of ligand attachment on the CI bond dissociation process  cAUG a17354-173640 v1213 aThe influence of the ligand attachment on the activation process of carbon halogen bond on small sized aluminum nanoclusters are investigated using density functional theory. Attaching suitable ligand to metal clusters is among the widely popular techniques often used by experimentalists in order to stabilize metastable clusters. In depth theoretical investigations have shown that based on the jellium configuration of the cluster, attaching an electron withdrawing ligand can either make a cluster more reactive toward the C-I dissociation or may convert the cluster relatively inert. The alteration of the activation barriers and other associated parameters due to ligand attachment are included in this paper along with additional calculations and explanations. The study also shows that even the reaction parameters of specific magic clusters can be significantly altered via ligand attachment. The activation process of small molecules on metal clusters are of crucial importance for the development of material science and cluster chemistry. The present investigation will therefore be useful for better understanding of the properties of the ligated clusters as well as may also aid the experimentalists toward controlling the reactivity of a specific cluster as required.1 aSengupta, Turbasu1 aSamanta, Bipasa1 aPal, Sourav uhttps://library.ncl.res.in/content/effect-ligand-attachment-c-i-bond-dissociation-process-aluminum-nanoclusters-dft01695nas a2200157 4500008004100000245009700041210006900138260000800207300001400215490000800229520112100237100002201358700002301380700001601403856011801419 2017 eng d00aMechanistic investigation of the carbon-iodine bond activation on the niobium-carbon cluster0 aMechanistic investigation of the carboniodine bond activation on cSEP a5335-53470 v2 3 a

The activation process of carbon-iodine (C-I) bond on neutral and cationic niobium metcars (Nb8C12) is investigated using density functional theory and related computational techniques. Metallocarbohedrenes or metcars are a class of stable metal-carbide clusters of specific stoichiometry and of great interest to cluster chemists since their first discovery. The detailed reaction mechanism along with the overall energy profile of the C-I dissociation reaction on niobium metcar and its cations is presented in this paper. The tunneling-corrected rate constants and their related reaction parameters such as the pre-exponential factor are also included alongside. The major differences between the reaction mechanism of the neutral and cationic metcars are also highlighted as well. Despite the available experimental results, the C-I bond dissociation on metcars has remained an unexplored problem in the theoretical and computational domains. Thus, the present investigation can fill in the gap and may also provide new insights provoking further developments in cluster and materials chemistry in future.

1 aSengupta, Turbasu1 aKhan, Muntazir, S.1 aPal, Sourav uhttps://library.ncl.res.in/content/mechanistic-investigation-carbon-iodine-bond-activation-niobium-carbon-cluster01065nas a2200169 4500008004100000022001500041245011300056210006900169260000800238300001600246490000800262520043700270100002000707700002200727700001600749856013000765 2018 eng d a 1932-744700aSpecificity of amino acid-aluminum cluster interaction and subsequent oxygen activation by the above complex0 aSpecificity of amino acidaluminum cluster interaction and subseq cDEC a28310-283230 v1223 aAmino acid aluminum cluster complex has been shown to be a promising oxygen molecule activator and has the potential to dissociate O-O bond on the cluster surface. The study of the complex also reveals specificity of amino acid to aluminum cluster in the above complex, which can be used in the detection of amino acid. The results have been obtained by the density functional theory at the B3LYP/6-311++g(d,p) level of calculation.1 aSamanta, Bipasa1 aSengupta, Turbasu1 aPal, Sourav uhttps://library.ncl.res.in/content/specificity-amino-acid-aluminum-cluster-interaction-and-subsequent-oxygen-activation-above01511nas a2200241 4500008004100000022001400041245004700055210004600102260000800148300000600156490000700162520083900169653002201008653003401030653001801064653000801082653001901090653002401109100002001133700002201153700001601175856007801191 2019 eng d a1610-294000aAluminum cluster for CO and O-2 adsorption0 aAluminum cluster for CO and O2 adsorption cJAN a20 v253 a

Low temperature oxidation of CO to CO2 is an important process for the environment. Similarly adsorption of CO from the releasing sources is also of major concern today. Whereas the potential of gold and silver clusters is well proven for thecatalysis of the above mentioned reaction, the potential of aluminum (Al) clusters remains unexplored. The present study proves that, similar to the transition metals, Al clusters can also be used for adsorption of gases. We first tested the potential of Al cluster as adsorbents for CO. The high binding energy (BE) values prove that Al clusters can be used for adsorbing both CO and O-2. Since oxygen binding is more facile, we adsorbed oxygen on Al and then checked the effect of this O-2 on the BE of CO. The results were obtained by DFT calculations at M062X/TZVP level of theory.

10aAluminum clusters10aCharge decomposition analysis10aCO adsorption10aDFT10aO-2 adsorption10aWiberg bond indices1 aSamanta, Bipasa1 aSengupta, Turbasu1 aPal, Sourav uhttps://library.ncl.res.in/content/aluminum-cluster-co-and-o-2-adsorption