|
|
Left: 0.1 millisecond of actual compression process at 10^3/sec strain-rate
Right: few picoseconds zoomed in around nucleation events of leading Shockley partial dislocation
- Some research I have dabbled in
- Some papers, preprints and talks
- When the taught becomes a teacher
- Links
Research Interests
- I am interested in developing algorithms to bridge the time-scale gap between experiments (milliseconds to seconds and longer) and computer simulations (nanoseconds and slower). I am also applying these algorithms to study problems inaccessible through ordinary MD simulations. Currently I am focusing on dislocation nucleation in nanopillars. Please see publications below for more on this!
- I have also been involved in developing interatomic potentials for various actinide oxides through state of the art ab initio calculations (DFT and DFT+U since these materials have localized and strongly correlated electrons). The challenge here which I addressed was to come up with potential forms that can be used in classical molecular dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. Another challenge was to incorporate ab initio results as well as experimental observations (example being thermal expansion data) into the potential generation process in a computationally efficient fashion. The third significant challenge was to ensure that the interactions developed are transferable: for instance the interaction potential of 2 Uranium and Oxygen ions should be rather insensitive to what is in their vicinity.
- In the past, I have been interested in (and still am!) computing alloy phase diagrams - through the Cluster Variation Method (CVM) and otherwise. I have also used Monte Carlo simulations to study one-dimensional models of stacking faults in crystals (using the Ising Model), and 2-dimensional & 3-dimensional models of grain boundaries in alloys (using an Ising-Potts coupled Model). In the stacking fault project, my interest was in quantifying the single crystal X-ray peak broadening. In the grain boundary project, I tried to understand the effects of phase separation in alloys on the accompanying grain boundaries. Do check out the papers
below for more details on these.
Publications
- Hybrid deterministic and stochastic approach for efficient atomistic simulation at long time scales
![[pdf]](pdficon_small.gif)
P. Tiwary and A. van de Walle Physical Review B (Rapid Communication) 84 2011 pg.100301
- Interatomic potentials for mixed
oxide and advanced nuclear fuels
P. Tiwary, A. van de Walle, B. Jeon and N. Gronbech Jensen Physical Review B 83 2011 pg.094104
- Ab initio construction of interatomic potentials for uranium dioxide across all interatomic distances
P. Tiwary, A. van de Walle, and N. Gronbech Jensen, Physical Review B 80 2009 pg.174302
- Cluster variation investigation of phase equilibria in Fe-Co system using simulated annealing approach
P. Tiwary and S.K. Ghosh, Computational Materials Science 39 2007 pg.788
- Scaling behaviour of pair correlation functions for randomly faulted hexagonal close-packed structures
P. Tiwary and D. Pandey, Acta Crystallographica Section A: Foundations of Crystallography 63 2007 pg.289
- An analytical expression for the characteristic length scale for randomly faulted hexagonal close-packed structures
P. Tiwary and D. Pandey, Acta Crystallographica Section A: Foundations of Crystallography 63 2007 pg.481
Working Papers
- Realistic time-scale fully atomistic simulations of surface nucleation of dislocations in pristine nanopillars
P. Tiwary and A. van de Walle, submitted to The Journal of Mechanics and Physics of Solids
- Monte Carlo simulations of grain
boundary effects on spinodal decomposition
P. Tiwary and T.A. Abinandanan
Talks
- Hybrid Deterministic and Stochastic Approach for Long Time Scale Atomistic Simulations: Contributed talk at TMS meeting, Florida, March 2012
- Hybrid Monte Carlo-Molecular Dynamics technique for long time-scale Molecular Dynamics simulations: Seminar at Materials Science & Technology Division, LANL, Los Alamos, February 2012
- Hybrid Monte Carlo-Molecular Dynamics technique for long time-scale Molecular Dynamics simulations: Seminar at Department of Materials Science & Engineering, MIT, Boston, September 2011
- Biased Monte Carlo technique to accelerate Molecular Dynamics simulations of rare events: Contributed talk at American Physical Society March Meeting 2011, Dallas, Texas
- Biased Monte Carlo technique to accelerate Molecular Dynamics simulations of rare events: Seminar at Department of Materials Engineering , Indian Institute of Science, Bangalore, India, March 2011
- Biased Monte Carlo technique to accelerate Molecular Dynamics simulations of rare events: Seminar at Theoretical Chemistry Section , Bhabha Atomic Research Centre, Mumbai,India, March 2011
- Building a Virtual Materials Laboratory with the help of Thermodynamics and Quantum mechanics: Seminar at Center for the Science and Engineering of Materials, Caltech, September 2010, Pasadena
Teaching
- In the winter quarters of 2008-09 and 2009-10, I TA'ed MS 131: Structure & Bonding in Materials. The class comprised around 25 students ranging from senior undergraduates to first year Graduate students (mostly) and second year Graduate students. My duties comprised grading all homeworks, holding regular office hours/recitation sessions and an occasional 90 minute lecture. Both years, it was a very satisfying experience!
In winter 2010-11, I TA'ed APh105b: States of Matter. This mostly comprised Classical Statistical Mechanics.
Miscellaneous Links
- The elusive chemical potential
R. Balerlein, American Journal of Physics 69 2001 pg.423
- Easy to use and integrate code for calculating Bond Order Parameter to determine local crystallinity