Theoretical chemistry: statistical mechanics of complex condensed matter systems
Research in our group encompasses different areas of condensed matter theory, including the statistical mechanics of complex fluids, polymer physics and stochastic processes. Over the last few years, we have been especially interested in developing theoretical models of the dynamics and reactivity of biological macromolecules, with a view to understanding cellular events at the molecular level. Among the problems that we have been pursuing are the following
Confined polymer dynamics
Calculations of the transport and conformational properties of continuum chains in narrow slits
We have been able to show that on length scales of the inter-wall separation, hydrodynamic interactions between different chain segments – usually quite strong – are screened out, and that the diffusivity and relaxation times of Gaussian chains exhibit power laws in the chain length, with logarithmic corrections.
Calculations of flow effects on polymers in capillaries
Although widely studied in the bulk, polymer-flow interactions have been much less studied in the presence of surfaces. Using a Rouse-Zimm approach, along with a variant of the nonlinear elastic model of chain inextensibility, we have determined the steady-state extension of a sheared polymer in a narrow cylindrical tube, and have found that the chain’s fractional extension is much smaller than its bulk value. This finding appears to reflect the screening of hydrodynamic interactions by the surface.
Calculations of reactivity in enclosed viscoelastic media
Biochemical reactions inside cells are typically subject to the effects both of the cell’s boundaries and of the viscoelasticity of its contents. To probe these effects further, we have been studying how they influence one particular reaction – the diffusion-limited cyclization of long polymers. Specifically, we have determined how the cyclization time of a flexible chain scales with its length when the chain is confined to a sphere, and when its dynamics are modulated by colored Gaussian noise
Calculations of the stochastic binding of tethered polymers to neutral or reactive surfaces
Communication between living cells is often mediated by the binding of proteins or other polymers to surface-attached receptors, and is typically stochastic. We have been developing methods to explore the first-passage dynamics of polymers that interact with planar surfaces, and have shown how these methods yield information about binding-time statistics that can be compared with experiment.
These various approaches to confined polymer dynamics are currently being extended in different directions.
A. Ghosal and B. J. CherayilTo appear in J. Stat. MechDOI:
A. Ghosal and B. J. CherayilJ. Stat. Mech. P10012 (2015)DOI: 10.1088/1742-5468/2015/10/P10012
Dynamics of the reaction between the free end of a tethered self-avoiding polymer and a flat penetrable surface: a renormalization group studyB. J. Cherayil and P. BhattacharyyaJ. Chem. Phys. 140, 234902 (2014)DOI: 10.1063/1.4882357
P. Bhattacharyya and B. J. CherayilJ. Chem. Phys. 138, 244904 (2013)DOI: 10.1063/1.4811332
P. Bhattacharyya and B. J. CherayilJ. Chem. Phys. 137, 194906 (2012)DOI: 10.1063/1.4765295
P. Bhattacharyya, R. Sharma and B. J. CherayilJ. Chem. Phys. 136, 234903 (2012)DOI: 10.1063/1.4729041
Force distribution function of an oscillator model of polymer stretching at constant velocityR. Sharma and B. J. CherayilJ. Stat. Mech. P05019 (2012)DOI: 10.1088/1742-5468/2012/05/P05019
R. Sharma and B. J. CherayilPhys. Rev. E 83, 0411805 (2011)DOI: 10.1103/PhysRevE.83.041805
Single-molecule thermodynamics: The heat distribution function of a charged particle in a static magnetic fieldD. Chatterjee and B. J. CherayilJ. Stat. Mech.: Theory Exp. P03010 (2011)DOI: 10.1088/1742-5468/2011/03/P03010
D. Chatterjee and B. J. CherayilPhys. Rev. E 82, 051104 (2010)DOI: 10.1103/PhysRevE.82.051104