Strings and Things

  VQE Variational Quantum Eigensolver (VQE)-style model to optimize the energy landscape of the FeMo cofactor system. ⚛️ What We'll Do We'll simulate the FeMoco cluster as a quantum Hamiltonian and use a variational quantum circuit to minimize the ground state energy , similar to how: VQE finds the lowest-energy electron configuration of a molecule.  Simplified Model of FeMoC for VQE While the full FeMoco has a complex multielectron Hamiltonian, we’ll simulate a toy model capturing: 3 sites (qubits) representing key iron or molybdenum redox centers , A Hamiltonian H with coupling terms: H = Z 0 Z 1 + Z 1 Z 2 + X 0 + X 1 + X 2​ This models: Redox coupling between centers ( Z Z terms), Electron tunneling/exchange ( X terms). 🛠️ Steps to Build the VQE Model                Define the Hamiltonian (using Pauli operators). Build a parameterized quantum circuit (ansatz) . Use a classical optimizer to va...

  How the FeMo Cofactor of Nitrogenase Breaks the Triple Bond in N₂ Breaking the triple bond in dinitrogen (N≡N) is one of the toughest chemical reactions in nature, requiring large activation energy due to its strength (~945 kJ/mol). Yet, nitrogenase , powered by its FeMo-cofactor (FeMoco) , performs this feat under ambient conditions . 🔬 Overview of FeMo Cofactor (FeMoco) The FeMoco is the active site of molybdenum-dependent nitrogenase, and it consists of: [Mo-7Fe-9S-C-homocitrate] cluster One central interstitial atom (carbon) suspected to play a stabilizing electronic role It acts as the redox center where electrons accumulate and transfer to N₂ , step by step, ultimately breaking its triple bond. 🧩 Mechanism: How FeMoC Breaks N≡N 1. Substrate Binding N₂ binds at or near the Mo or Fe6 site on the FeMoco cluster. Hydrogen bonding and conformational changes help stabilize the binding. 2. Electron Accumulation The nitrogenase complex sequentially...