BS-MS student at Indian Institute of Science Education and Research, Kolkata (Chemistry Major, Computer Science Minor, CGPA 8.2). My work sits at the intersection of computational chemistry, AI/ML research, and information retrieval. I co-founded two MeitY-funded deeptech startups and have published at ECIR 2026, FIRE 2025, and TREC 2024.
| Current Research | Hybrid RAG architectures, DFT-based catalyst modelling, query reformulation for NLP |
| Learning | LAMMPS, HPC workflows, advanced DFT, Agentic AI frameworks |
| Looking to Collaborate | ML, Data Science, Molecular Simulations, Quantum Chemistry |
| Contact | sbs22ms076@iiserkol.ac.in |
First principles, then force fields. — Every simulation is an argument about reality. I compute to test the argument, not to decorate it. If the HOMO–LUMO gap disagrees with the experiment, the gap is not wrong — the model is.
Retrieval over memorisation. — A model that cannot cite its sources is an opinion engine. Whether it is a language model or a spectroscopy reference, the answer must trace back to evidence.
Ship the negative result. — The failed catalyst, the ablation that lost, the retrieval run that underperformed BM25 — these are data. Science compounds only when the null results are public.
| Year | Venue | Title |
|---|---|---|
| 2026 | ECIR 2026 (34.5% acceptance) | AgriIR: A Scalable Framework for Domain-Specific Knowledge Retrieval |
| 2025 | FIRE 2025 | Hierarchical Opinion Classification using Large Language Models |
| 2024 | TREC 2024 (NIST) | IISERK@ToT_2024: Query Reformulation and Layered Retrieval |
| WIP | To be submitted | Computational Modeling of [VO(SALIEP)(DTP)] as Water Reducing Catalyst (DFT/B3LYP) |
Can you replicate the complex from the computational chemistry research? Choose wisely — wrong paths teach too.
Step 1 — Choose your central metal
You need a redox-active transition metal capable of oxo-coordination for water reduction.
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Select Vanadium (V)
Correct instinct. Vanadium(IV) oxo-complexes are known water-reduction catalysts — the d¹ electron gives you EPR handle too.
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Add Salen-type ligand (SALIEP)
SALIEP provides strong N/O donors that stabilise V(IV). Now choose the co-ligand.
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Add dithiophosphate (DTP)
You built [VO(SALIEP)(DTP)] — the exact target complex from the DFT/B3LYP study. Run Gaussian with B3LYP/6-311G(d,p), compute MO energies, map the water-reduction pathway. The V=O stretch should land near 965 cm⁻¹ — if it does, your geometry converged.
Add bipyridine (bpy)
Interesting coordination — but bpy makes the complex too inert for proton-coupled electron transfer here. Swap in dithiophosphate (DTP).
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Add only H₂O as ligand
Water alone will not chelate stably — it exchanges too fast. Try a stronger donor like SALIEP.
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Select Iron (Fe)
Iron catalyses plenty of chemistry — but this specific DFT study uses Vanadium. Try again.
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Select Zinc (Zn)
d¹⁰ — diamagnetic, redox-silent. No unpaired electron, no EPR signal, no water reduction here. Pick a metal with available d-electrons.
Design the retrieval architecture step by step — same decisions I made for the IISER-K intranet system.
Step 1 — Choose your retriever
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Dense retrieval only (vector embeddings)
Handles semantic similarity well, but misses exact keyword matches for rare technical terms. Upgrade?
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Add BM25 sparse retrieval in parallel
Now you have hybrid retrieval. How do you merge the two ranked lists?
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Reciprocal Rank Fusion (RRF)
Perfect. RRF combines ranked lists without score calibration. Add HyDE (hypothetical document embeddings) for query refinement and wrap in a Streamlit UI — you have replicated the ECIR 2026 / IISER-K intranet system.
Weighted linear score combination
Works, but requires per-domain score calibration — brittle across corpora. RRF is more robust. Try again.
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BM25 sparse only
Fast and interpretable, but misses paraphrases. Upgrade to hybrid for better recall.
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Fine-tune a cross-encoder re-ranker on 50 labelled queries
Legitimate architecture — but with 50 labels you will overfit in an afternoon. Hybrid + RRF gets you further with zero labels. Try the label-free path first.
Solvate the vanadium complex and keep it intact for 500 ns. Three choices, one stable trajectory.
Step 1 — Pick the ensemble
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NVT (fixed volume, thermostat only)
Stable and simple — but with fixed volume you cannot model the solvent density change as the complex relaxes. Fine for a first equilibration, though. Proceed.
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Thermostat: Nosé–Hoover
Smooth, deterministic, canonical ensemble. Now the integration timestep:
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2 fs with constrained bonds (SHAKE)
Stable trajectory. Constraints remove the fast X–H vibrations, 2 fs resolves the V=O stretch, and over 500 ns the RMSD plateaus near 1.2 Å — complex intact, no dissociation. This is the production setup.
5 fs bare (no constraints)
Blown up. The O–H stretch oscillates at ~10 fs period — a 5 fs step integrates it as energy gain and your simulation detonates within picoseconds. Constrain bonds and drop to 2 fs.
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Thermostat: direct velocity rescaling every step
It will hold the temperature — but it distorts dynamics and gives wrong fluctuation statistics. Nosé–Hoover samples the canonical ensemble properly.
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NVE (no thermostat)
Pure Newtonian dynamics — beautiful, but any drift from the equilibrated state never gets corrected. Use NVT for production.
Every stat service below was verified alive (HTTP 200, valid SVG) at embed time. Dead endpoints — github-readme-stats (deployment paused), profile-trophy and contributor-stats (disabled), streak-stats herokuapp (shut down) — were removed in the v2 redesign rather than left rendering error images.
flowchart LR
A[Problem Statement] --> B[Literature Review]
B --> C[Dataset & Baseline]
C --> D[Model Design]
D --> E[Experiments & Ablations]
E --> F{Results Satisfactory?}
F -- No --> D
F -- Yes --> G[Paper Writing]
G --> H[Peer Review]
H --> I[Publication ECIR / FIRE / TREC]
I --> J[Open-Source Release]
style A fill:#1e3a5f,stroke:#58a6ff,color:#c9d1d9
style I fill:#2d1f4a,stroke:#d2a8ff,color:#c9d1d9
style J fill:#1f3a2d,stroke:#56d364,color:#c9d1d9



