August 25, 2014 at 4.00 pm in AG-69
Perturbative Approximations to Spin Flip Coupled Cluster Singles Doubles - Application to Bond Breaking Problem
Spin flip equation of motion coupled cluster (EOM-SF-CC) can correctly treat situations involving electronic degeneracies or near degeneracies, e.g, bond breaking, di- and tri-radicals etc. However, for large systems EOM-SF-CC (even in single and double excitations) is
computationally prohibitively expensive. Therefore, earlier approximations to EOM-SF-CC methods such as spin flip configuration interaction singles with perturbative doubles (SF-CIS(D)) has been proposed. In this talk, I will present a new perturbative approximation to EOM-SF-CC, which has been found to be more accurate than the earlier SF-CIS(D). The capabilities, advantages and timings of the new approach will be demonstrated through bond breaking problems, oxirane ring opening and cyclo-butadiene automerization reaction.
1. A. K. Dutta, S. Pal And D. Ghosh, Perturbative approximations to single and double spin flip equation of motion coupled cluster singles doubles methods, J. Chem. Phys., 139, 124116 (2013).
2. D. Ghosh, Perturbative approximation to hybrid equation of motion coupled cluster / effective fragment potential method, J. Chem. Phys., 140, 094101 (2014).
July 28, 2014 at 4.00 pm in AG-69
Regio- and Stereo-selective Approaches for Glycoconjugate Synthesis
Cell surface carbohydrates in the form of glycoconjugates play vital roles in various important life processes. They are structurally complex and diverse. Since they are present in microheterogeneous forms in nature, they cannot be isolated in acceptable amount and purity. Chemical synthesis, however challenging, provides an opportunity for obtaining structurally well defined and chemically pure glycoconjugates for biological studies. Regio- and stereoselective approaches make the synthesis less arduous and more efficient. Recent examples from our studies on the synthesis of complex carbohydrates will be presented.
December 8, 2014 at 4.00 pm in AG-66
Title : Exploring Energy Landscapes : From Molecules to Nanodevices
The potential energy landscape provides a conceptual and computational framework forinvestigating structure, dynamics and thermodynamics in atomic and molecular science. This talk will summarise new approaches for global optimisation, quantum dynamics, the thermodynamic properties of systems exhibiting broken ergodicity, and rare event dynamics. Applications will be presented that range from prediction and analysis of high-resolution spectra, to conformational changes of biomolecules and coarse-grained models of mesoscopic structures.
D.J. Wales, Curr. Op. Struct. Biol., 20, 3-10 (2010)
D.J. Wales, J. Chem. Phys., 130, 204111 (2009)
B. Strodel and D.J. Wales, Chem. Phys. Lett., 466, 105-115 (2008)
D.J. Wales and T.V. Bogdan, J. Phys. Chem. B, 110, 20765-20776 (2006)
D.J. Wales, Int. Rev. Phys. Chem., 25, 237-282 (2006)
D.J. Wales, "Energy Landscapes", Cambridge University Press, Cambridge, 2003
July 21, 2014 at 4.00 pm in AG-69
Towards Understanding the Mechanism of Amyloid Beta Mediated Toxicity in Alzheimer's Disease
June 16, 2014 at 4.00 pm in AG-69
Understanding Bio-molecular Interactions for Novel Drug Discovery: Biophysical Approach
More than the synthesis of a large number of new molecules, the challenge faced by the pharmaceutical industries is to exploit the wealth of these compounds and relate their activity to the mode of interaction with the relevant targets of biological importance. This requires an in-depth understanding of intermolecular interactions responsible for therapeutic intervention. Recent advances in methodologies to unravel the intricate intermolecular interactions have added tremendous amount of understanding in such phenomenon. The talk will address biophysical approach to understand the binding of some antibiotic and anti cancer drugs with serum albumin in view of the importance of drug-protein interactions in drug delivery. This requires a detailed structural, conformational and energetic investigation. The talk will also address the screening of GlaxoSmithKline compound library in search of tuberculosis active compounds which target Mycobacterium tuberculosis topoisomerase-I through stabilized cleaved topoisomerase I - DNA complex mechanism and serve as Mycobacterium tuberculosis topoisomerase I poison to cure XDR and MDR tuberculosis.