collaborators

10 papers

physics.chem-ph2026

Perturbatively Corrected Linear Response Selected Configuration Interaction

Peter Reinholdt, Erik Kjellgren, Jacob Kongsted

Selected configuration interaction (SCI) methods have emerged as powerful, lower-cost alternatives to full configuration interaction (FCI) for ground- and excited-state energies. S…

quant-ph2026

Orbital-optimized spin-adapted multistate contracted VQE for excited states and properties on quantum hardware

Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt +3

We introduce the orbital-optimized multistate contracted variational quantum eigensolver (oo-MC-VQE) method with spin-adapted operators for the computation of ground and excited st…

quant-ph2026

State-Averaged Quantum Algorithms for Multiconfigurational Surface Chemistry: A Benchmark on Rh@TiO2(110)

Ernst Dennis Lægteskov Binau Larsson, Erik Kjellgren, Peter Reinholdt +1

Accurate modeling of surface catalytic processes often requires methods capable of describing strong correlation, charge transfer, and multiple closely lying electronic states. Whi…

quant-ph2025

Cost-effective scalable quantum error mitigation for tiled Ansätze

Oskar Graulund Lentz Rasmussen, Erik Kjellgren, Peter Reinholdt +4

We introduce a cost-effective quantum error mitigation technique that builds upon the recent Ansatz-based gate and readout error mitigation method (M0). The technique, tiled M0, le…

physics.chem-ph2025

Orbital-Optimized Unitary Coupled Cluster for Indirect Nuclear Spin-Spin Coupling Constants within a Quantum Linear Response Framework

Juliane H. Fuglsbjerg, Peter Reinholdt, Erik Kjellgren +4

We present a quantum linear response (qLR) approach within an active-space framework for computing indirect nuclear spin-spin coupling constants, a key ingredient in NMR spectra pr…

physics.chem-ph2025

Linear Response Selected Configuration Interaction

Peter Reinholdt, Erik Kjellgren, Jacob Kongsted

In this work, we extend selected configuration interaction (SCI) methods beyond energies and expectation values by introducing a linear response (LR) framework for molecular respon…