01187nas a2200217 4500008004100000022001400041245008400055210006900139260000800208300001200216490000800228520043300236653003800669653004800707653001600755653003800771100001700809700001600826700001800842856010900860 2013 eng d a0026-897600aInteratomic coulombic decay in (HF)n,(n=2-3) clusters using CAP/EOM-CCSD method0 aInteratomic coulombic decay in HFnn23 clusters using CAPEOMCCSD  cNOV a669-6730 v1123 a

The equation-of-motion coupled-cluster method along with the complex absorbing potential has been applied to study the interatomic Coulombic decay mechanism in hydrogen-bonded clusters. We have applied this method to calculate the lifetime of the F 2s inner-valence ionised state of (HF)(n) (n = 2-3) clusters. The lifetime is found to be very short and decreases substantially with increasing the number of HF monomer.

10acomplex absorbing potential (CAP)10aequation-of-motion coupled-cluster (EOM-CC)10aHF clusters10ainteratomic Coulombic decay (ICD)1 aGhosh, Aryya1 aPal, Sourav1 aVaval, Nayana uhttps://library.ncl.res.in/content/interatomic-coulombic-decay-hfnn2-3-clusters-using-capeom-ccsd-method01630nas a2200181 4500008004100000022001400041245010700055210006900162260007100231300001400302490000700316520092200323100002701245700002001272700001801292700001601310856012201326 2014 eng d a1549-961800aIntermediate hamiltonian fock space multireference coupled cluster approach to core excitation spectra0 aIntermediate hamiltonian fock space multireference coupled clust a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP a3656-36680 v103 a

The Fock space multireference coupled cluster (FSMRCC) method provides an efficient approach for the direct calculation of excitation energies. In intermediate Hamiltonian (IH-FSMRCC) formulation, the method is free from intruder state problems and associated convergence difficulties, even with a large model space. In this paper, we demonstrate that the IH-FSMRCC method with suitably chosen model space can be used for the accurate description of core excitation spectra of molecules, and our results are in excellent agreement with the experimental values. We have investigated the effect of choice of model space on the computed results. Unlike the equation-of-motion (EOM)-based method, the IH-FSMRCC does not require any special technique for convergence and in singles and doubles approximation gives a performance comparable to that of the standard EOMEE-CCSD method, even better in some of the cases.

1 aDutta, Achintya, Kumar1 aGupta, Jitendra1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/intermediate-hamiltonian-fock-space-multireference-coupled-cluster-approach-core-002036nas a2200193 4500008004100000022001400041245016500055210006900220260007900289300001100368490000700379520123500386100001801621700002001639700002201659700001801681700001601699856012701715 2015 eng d a2469-992600aImplementation of the Z-vector method in the relativistic-coupled-cluster framework to calculate first-order energy derivatives: Application to the SrF molecule0 aImplementation of the Zvector method in the relativisticcoupledc aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMER PHYSICAL SOCcMAR a0305030 v913 a

The molecular dipole moment and magnetic hyperfine-structure constant demand an accurate wave function far from the nucleus and in the near nuclear region, respectively. We, therefore, employ the so-called Z-vector method in the domain of relativistic-coupled-cluster theory to calculate the first-order property of molecular systems in their open-shell ground-state configuration. The implemented method is applied to calculate the molecular dipole moment and parallel component of the magnetic hyperfine-structure constant of the SrF molecule. The results of our calculation are compared with the experimental and other available theoretically calculated values. We are successful in achieving good accordance with the experimental results. The result of our calculation of the molecular dipole moment is in the accuracy of similar to 0.5%, which is clearly an improvement over the previous calculation based on the expectation value method in the four-component coupled-cluster framework [V. S. Prasannaa et al., Phys. Rev. A 90, 052507 (2014)]. Thus, it can be inferred that the Z-vector method can provide an accurate wave function in both the near and far nuclear region, which is evident from our calculated results.

1 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/implementation-z-vector-method-relativistic-coupled-cluster-framework-calculate-first-101653nas a2200217 4500008004100000022001400041245014100055210006900196260000800265300001300273490000800286520083500294653002501129653004701154653001501201653003801216100001701254700001601271700001801287856013001305 2021 eng d a0026-897600aInteratomic Coulombic decay in Neon-Helium cluster: a complex absorbing potential based equation-of-motion coupled cluster investigation0 aInteratomic Coulombic decay in NeonHelium cluster a complex abso cMAY ae18843000 v1193 a

The interatomic Coulombic decay (ICD) of the Ne(2s(-1)) and Ne(2s(-1)2p(-1)) states in neon-helium dimer is studied using highly accurate complex absorbing potential based equation-of-motion coupled cluster (CAP-EOMCC) method. The ICD decay process for the Ne(2s(-1)) state in neon-helium dimer is closed at its equilibrium bond distance. However, the decay channel is open at large bond distance of 6.2 angstrom. The decay channel for the double ionised Ne(2s(-1)2p(-1)) state is open at 3.46 angstrom. From our calculations, we have noticed that the decay rate of Ne(2s(-1)2p(-1)) state in neon-helium dimer is four times faster compared to the Ne(2s(-1)) state. We have also investigated how the decay rate of Ne(2s(-1)) state in neon-helium cluster varies in the presence of different helium environment. [GRAPHICS] .

10adouble ionised state10aequation-of-motion coupled cluster (EOMCC)10aHe droplet10ainteratomic Coulombic decay (ICD)1 aGhosh, Aryya1 aPal, Sourav1 aVaval, Nayana uhttps://library.ncl.res.in/content/interatomic-coulombic-decay-neon-helium-cluster-complex-absorbing-potential-based-equation02601nas a2200241 4500008004100000022001400041245018300055210006900238260000800307300001100315490000800326520170900334653002002043653002502063653002702088653002102115653001302136100002002149700001602169700001802185700002602203856013002229 2023 eng d a1387-181100aInsights into adsorption of various gases on extra-framework cations of zeolite: a dispersion corrected DFT study on zeolite cluster models with Li plus , Na plus and K plus ions0 aInsights into adsorption of various gases on extraframework cati cNov a1127390 v3613 a

Design of an economical and sustainable gas separation material is relevant in several industrial processes. Zeolites with tunable pore sizes are ideal molecular sieves of many gases. The adsorption centers of these molecular sieves are extra-framework Lewis acid centers. In this study, we attempt to delineate the electronic properties of such centers (Li+, Na+ and K+) and their sorption properties towards N2, O2, CO, CO2 and H2. Negative framework of zeolites are modeled using different cluster models that present distinct electronic environment and role of this environment on the Lewis acidity of the cation. The sorption property towards different gases is evaluated using dispersion corrected DFT studies. The results obtained are benchmarked for one of the studied model using CCSD calculations. The results indicate that while the local environment modulates the adsorption properties, the relative adsorption properties between different ions follow the same order irrespective of the type of negative framework modeled. This reveals that intrinsic atomic properties of the charge compensating cations drive the sorption properties of the zeolites. Adsorption energies compounded with the analysis of IR stretching frequencies of the adsorbed gases reveals that Li centers shows molecular adsorption (charge donation to the cationic centers) towards N2 as compared to O2 and towards CO2/CO as compared to H2, demonstrating the applicability of Li-Zeolites as ideal membranes for oxygen concentrators and syngas separation. These adsorption studies are ratified by the BOMD simulations at 300 K, where H2 and O2 desorbs while N2, CO and CO2 remains adsorbed to the cationic site.

10aBOMD simulation10aCO/CO2/H2 separation10aExtra-framework cation10aN2/O2 separation10azeolites1 aDevasia, George1 aKumar, Ravi1 aVaval, Nayana1 aKrishnamurty, Sailaja uhttps://library.ncl.res.in/content/insights-adsorption-various-gases-extra-framework-cations-zeolite-dispersion-corrected-dft