@article { ISI:000256005300018, title = {First principles calculations of thermal, equations of state and thermodynamical properties of MgH2 at finite temperatures}, journal = {Computational Materials Science}, volume = {42}, number = {3}, year = {2008}, month = {MAY}, pages = {510-516}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

We present the first principles calculations of the thermodynamical properties of magnesium hydride (MgH2) over a temperature range of 0-1000 K. The phonon dispersions are determined within the density functional framework and are used to calculate the free energy of MgH2 within the quasiharmonic approximation (QHA) at each cell volume and temperature T. Using the free energies the thermal equation of state (EOS) is derived at several temperatures. From the thermal EOS structural parameters such as the equilibrium bell volume (V-0) and elastic properties, namely, bulk modulus (K-0) and its pressure derivative (K-0({\textquoteright})) are computed. The free energies are also used to calculate various thermodynamical properties within QHA. These include internal energy E, entropy S, specific heat capacity at constant pressure C-P, thermal pressure P-thermal(V,T) and volume thermal expansion Delta V/V (\%). The good agreement of calculated values of S and Cp with experimental data exhibits that QHA can be used as a tool for calculating the thermodynamical properties of MgH2 over a wide temperature range. P-thermal(V,T) increases strongly with T at all the volumes but it is a slowly varying function of volume for T = 298-500 K. According to Karki [B.B. Karki, Am. Miner. 85 (2000) 1447] such volume based variations can be neglected and so it is possible to estimate the thermal EOS only with the knowledge of the measured P-thermal(V,T) versus temperature at ambient pressure and isothermal compression data at ambient temperature. Temperature dependence of Delta V/V(\%) shows that V-0 increased with increase in temperature. However, the percentage decrease in K-0 superseded this percentage increase in V-0 even at temperatures moderately higher than 298 K. Therefore, we suggest application of temperature (T \> 298 K) as an approach to enhance the hydrogen storage capacity of MgH2 because of its better compressibility at these temperatures. (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {equation of state, Hydrogen storage, lattice dynamics, magnesium hydride, Thermodynamic properties}, issn = {0927-0256}, doi = {10.1016/j.commatsci.2007.08.014}, author = {Kelkar, Tuhina and Kanhere, Dilip G. and Pal, Sourav} } @article { ISI:000267983100004, title = {First- and second-order electrical properties computed at the FSMRCCSD level for excited states of closed-shell molecules using the constrained-variational approach}, journal = {Journal of Chemical Physics}, volume = {131}, number = {2}, year = {2009}, month = {JUL}, pages = {024102}, publisher = {AMER INST PHYSICS}, address = {CIRCULATION \& FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA}, abstract = {

Fock space multireference coupled-cluster (FSMRCC) method emerged as an efficient tool to describe the electronic structure of nearly degenerate cases. Development of linear response has been one of the challenging problems in FSMRCC due to the multiple-root nature of the effective Hamiltonian. A response from any of the roots would span the space for getting the properties. Hence, all roots perturbed by the external field would proliferate the excited states. We recently developed the FSMRCC method for the efficient evaluation of analytic response properties using a constrained variation approach. In this paper, we present analytic dipole moments and polarizabilities of H2O, O-3, and CH+ molecules in low-lying excited states along with brief discussion of singlet triplet decoupling of (1,1) sector of FSMRCC resulting from spin adaptation. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3167796]

}, issn = {0021-9606}, doi = {10.1063/1.3167796}, author = {Bag, Arijit and Manohar, Prashant Uday and Vaval, Nayana and Pal, Sourav} } @article { ISI:000284635100022, title = {Fock space multi-reference coupled-cluster method for energies and energy derivatives}, journal = {Molecular Physics}, volume = {108}, number = {21-23, SI}, year = {2010}, month = {OCT}, pages = {PII 927961714}, publisher = {TAYLOR \& FRANCIS LTD}, address = {4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}, abstract = {

In this article, the development of Fock space multi-reference coupled-cluster method is reviewed. Molecular applications of the method for excitation and ionisation energies which took place at Quantum Theory Project have been discussed. Later developments of the method for energy derivatives have been presented along with pilot applications of molecular properties of radicals and excited states.

}, keywords = {coupled-cluster, difference energies, energy derivatives, Fock space, Multi-reference}, issn = {0026-8976}, doi = {10.1080/00268976.2010.522205}, author = {Pal, Sourav} } @article { ISI:000294386000007, title = {Finite temperature behavior of gas phase neutral Au-n (3 <= n <= 10) clusters: a first principles investigation}, journal = {Journal of Physical Chemistry C}, volume = {115}, number = {35}, year = {2011}, month = {SEP}, pages = {17278-17285}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

{Relativistic density functional theory (DFT) based molecular dynamical simulations are performed on gold clusters with 3-10 atoms (Au-n

}, issn = {1932-7447}, doi = {10.1021/jp2023605}, author = {De, Himadri Sekhar and Krishnamurty, Sailaja and Mishra, Deepti and Pal, Sourav} } @article { ISI:000311350000015, title = {First principle investigation on the thermal stability of a golden fullerene: a case study of Au-32}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {106-109}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Structural and electronic properties of Au-32 cluster are analyzed using relativistic density functional theory (DFT) based methods. Further, DFT based molecular dynamical (MD) simulations are performed on Au-32 golden fullerene with an aim of understanding its thermal stability at various working temperatures. Various conformations being populated at different temperatures of a cluster are analyzed. The study shows that the ground state icosahedral conformation is stable only up to 300 K and structure remains in a hollow conformation only up to 400 K. This clearly explains the reasons for failure by experimentalists in trapping the unique fullerene conformation in spite of the theoretical predictions of it being a very stable one. The above MD study also indicates that the bare fullerene Au-32 cluster (without any stabilizing ligands) can be used for potential catalytic applications only around room temperatures. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {Au-32 cluster, Born-Oppenheimer molecular dynamics, Density functional theory, Golden fullerenes, Relativistic effects}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.04.072}, author = {De, Himadri Sekhar and Krishnamurty, Sailaja and Pal, Sourav} } @article {42666, title = {Fock-space multi-reference coupled-cluster response with the effect of triples on dipole moment of ClO and SF radicals}, journal = {Journal of Chemical Sciences}, volume = {124}, year = {2012}, month = {JAN}, pages = {223-232}, doi = {10.1007/s12039-012-0220-x}, author = {Ravichandran, Lalitha and Bhattacharya, Debarati and Vaval, Nayana and Pal, Sourav} } @article { ISI:000318538100003, title = {Fock space multireference coupled cluster theory: study of shape resonance}, journal = {International Journal of Quantum Chemistry}, volume = {113}, number = {12}, year = {2013}, month = {JUN}, pages = {1690-1695}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

The complex absorbing potential along with correlated independent particle potential (CIP) Fock space multireference coupled cluster method is used for the study of resonances. We have studied shape resonance of e(-) - F-2, e(-) - N2O and e(-) -CO molecules. In particular, we have studied e(-) - F-2 scattering at different bond lengths to know whether F-2(-) is bound at the equilibrium bond length of F-2. (C) 2013 Wiley Periodicals, Inc.

}, keywords = {correlated independent particle potential, Fock-space multireference coupled cluster theory, shape resonance}, issn = {0020-7608}, doi = {10.1002/qua.24387}, author = {Bhattacharya, Sumantra and Vaval, Nayana and Pal, Sourav} }