Research Projects

Quantum Chemical Predictions for Clean Energy Materials

Quantum Chemical Simulations of Gas Sorption in Metal–Organic Frameworks: For the discovery of clean energy materials, I employed density functional theory and advanced Energy Decomposition Analysis to examine gas binding in metal–organic frameworks (MOFs). This work revealed the electrostatic, dispersion, polarisation, and charge-transfer components governing hydrogen sorption and led to predictions of multi-ligation pathways that substantially boost volumetric capacity. I also developed and optimised high-performance electronic structure code for large-scale quantum simulations.

Prediction of Multiple Hydrogen Ligation at the Primary Coordination Sphere of V(II) in a MOF.

Chakraborty, R., Carsch, K.M., Jaramillo, D.E., Yabuuchi, Y., Furukawa, H., Long, J.R. and Head-Gordon, M., 2022. The Journal of Physical Chemistry Letters, 13, pp.10471-10478.

With state-of-the art DFT simulations we predict the feasible ligation of two equivalents of hydrogen per open metal site, a discovery if realized experimentally can have a multiplicative effect for hydrogen storage in the solid state.

Ambient temperature hydrogen storage via vanadium(II)-dihydrogen complexation in a metal-organic framework

Jaramillo, D.E., Jiang, H.Z., Evans, H.A., Chakraborty, R., Furukawa, H., Brown, C.M., Head-Gordon, M. and Long, J.R., 2021. Journal of the American Chemical Society, 143(16), pp.6248-6256.

In this experimental collaboration with David Jaramillo (Long group), I simulated a Vanadium(II) MOF that displays near-optimal binding interactions for ambient temperature H2 storage.

Observation of an Intermediate to H2 Binding in a Metal–Organic Framework

Barnett, B.R., Evans, H.A., Su, G.M., Jiang, H.Z., Chakraborty, R., Banyeretse, D., Hartman, T.J., Martinez, M.B., Trump, B.A., Tarver, J.D. and Dods, M.N., 2021. Journal of the American Chemical Society, 143(36), pp.14884-14894.

In this experimental collaboration with Long Research Group, we helped characterize a physisorbed intermediate to hydrogen binding with constrained optimizations along the molecular PES

Quantum Chemical Modeling of Pressure-Induced Spin Crossover in Octahedral Metal-Ligand Complexes

Stauch, T., Chakraborty, R. and Head‐Gordon, M., 2019. ChemPhysChem, 20(21), pp.2742-2747.

This collaboration with Prof. Tim Neudecker (née Stauch) models spin crossover in transition metal complexes using a Hydrostatic Compression Force Field inspired by DFT.

Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package.

Epifanovsky, E., Gilbert, A.T., Feng, X., Lee, J., Mao, Y., Mardirossian, Chakraborty R, N., Pokhilko, P., White, A.F., Coons, M.P., Dempwolff, A.L. and Gan, Z., 2021. The Journal of chemical physics, 155(8), p.084801.

QChem 5 now has DFT-D4 dispersion corrections implemented!

Confinement Entropy from Numerical Partition Functions

Chakraborty R, Talbot J.J, Head-Gordon, Martin. In Prep

Simulations of confinement entropy are made challenging by exponential walls, both in electronic, and nuclear degrees of freedom. Here we simulate the effects of confinement on the entropy of gues molecules in nanoporous frameworks first under an uncoupled mode approximation, and with fully quantum mechanically coupled modes.

Generalised Pauli Exclusion Principle: Quantum Information Theory in Quantum Chemistry

Generalising the Pauli Exclusion Principle: Using affine inequalities inspired by Quantum Information Theory, I established one-electron theories that exceed standard Pauli constraints, ensuring pure-state electron occupations and enabling sparse ansätze for many-body quantum systems. I investigated these Generalised Pauli Conditions (GPCs) on atoms, molecules, and in open quantum systems, verifying their utility in detecting pure quantum states from single-particle occupations. By demonstrating GPC violations for ensemble density matrices, I underscored their sensitivity to entanglement and noise.

Sparsity of the wavefunction from the generalized Pauli exclusion principle

Chakraborty, R. and Mazziotti, D.A., 2018. The Journal of chemical physics, 148(5), p.054106.

We formulate here sparse representations for the N-fermion wavefunction based on General Pauli conditions that enforce global antisymmetry on N-fermion quantum states.

Sufficient condition for the openness of a many-electron quantum system from the violation of a generalized Pauli exclusion principle

Chakraborty, R. and Mazziotti, D.A., 2015. Physical Review A, 91(1), p.010101.

Here I derived sufficient conditions to detect noise in an N-fermion system sans a tomography of the N-particle density matrix.

Generalized Pauli conditions on the spectra of one-electron reduced density matrices of atoms and molecules

Chakraborty, R. and Mazziotti, D.A., 2014. Physical Review A, 89(4), p.042505.

This highlight from my graduate work studies the effect global antisymmetry constraints has on natural occupations number for pure quantum states that represent atoms and molecules.

Noise-Assisted Energy Transfer from the Dilation of the set of One-Electron Reduced Density Matrices

Chakraborty, R. and Mazziotti, D.A., 2017. The Journal of Chemical Physics, 146(18), p.184101.

This work looks at noise assisted energy transfer from a geometric perspective that involves the dilation of the set of accessible 1-RDMs with the introduction of quantum noise.

Role of Generalized Pauli Conditions in the Quantum Chemistry of Excited States

Chakraborty, R. and Mazziotti, D.A., 2016. International Journal of Quantum Chemistry, 116(10), pp.784-790.

Structure of the One-Electron Reduced Density Matrix from the Generalized Pauli Exclusion Principle

Chakraborty, R. and Mazziotti, D.A., 2015. International Journal of Quantum Chemistry, 115(19), pp.1305-1310.

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