9 papers · 1 filter
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…
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…
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…
Hyperfine Coupling Constants on Quantum Computers: Performance, Errors, and Future Prospects
Phillip W. K. Jensen, Gustav Stausbøll Hedemark, Karl Michael Ziems +6
We present the first implementation and computation of electron spin resonance isotropic hyperfine coupling constants (HFCs) on quantum hardware. As illustrative test cases, we com…
Exact closed-form expression for unitary spin-adapted fermionic singlet double excitation operators
Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt +3
We derive exact closed-form expressions for the matrix exponential of the anti-Hermitian spin-adapted singlet double excitation fermionic operators. These expressions enable the ef…
Divergences in classical and quantum linear response and equation of motion formulations
Erik Rosendahl Kjellgren, Peter Reinholdt, Karl Michael Ziems +3
Calculating molecular properties using quantum devices can be done through the quantum linear response (qLR) or, equivalently, the quantum equation of motion (qEOM) formulations. D…