63 citations · 138 across the 19 of their papers we have counts for
20 papers
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…
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…
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…
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…
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…
Redundant parameter dependencies in truncated classic and quantum Linear Response and Equation of Motion theory
Erik Rosendahl Kjellgren, Peter Reinholdt, Karl Michael Ziems +3
Extracting molecular properties from a wave function can be done through the linear response (LR) formalism or, equivalently, the equation of motion (EOM) formalism. For a simple m…
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…
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…
Critical Limitations in Quantum-Selected Configuration Interaction Methods
Peter Reinholdt, Karl Michael Ziems, Erik Rosendahl Kjellgren +3
Quantum Selected Configuration Interaction (QSCI) methods (also known as Sample-based Quantum Diagonalization, SQD) have emerged as promising near-term approaches to solving the el…
Self-consistent Quantum Linear Response with a Polarizable Embedding environment
Peter Reinholdt, Erik Rosendahl Kjellgren, Karl Michael Ziems +3
Quantum computing presents a promising avenue for solving complex problems, particularly in quantum chemistry, where it could accelerate the computation of molecular properties and…
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…
Electric Field Gradient Calculations for Ice VIII and IX using Polarizable Embedding: A Comparative Study on Classical Computers and Quantum Simulators
Dániel Nagy, Peter Reinholdt, Phillip W. K. Jensen +7
We test the performance of the Polarizable Embedding Variational Quantum Eigensolver Self-Consistent-Field (PE-VQE-SCF) model for computing electric field gradients with comparison…
Subspace methods for the simulation of molecular response properties on a quantum computer
Peter Reinholdt, Erik Rosendahl Kjellgren, Juliane Holst Fuglsbjerg +4
We explore Davidson methods for obtaining excitation energies and other linear response properties within quantum self-consistent linear response (q-sc-LR) theory. Davidson-type me…
X-ray Absorption Spectra for Aqueous Ammonia and Ammonium: Quantum Mechanical versus Molecular Mechanical Embedding Schemes
Sarai Dery Folkestad, Alexander C. Paul, Regina Paul +4
The X-ray absorption (XA) spectra of aqueous ammonia and ammonium are computed using a combination of coupled cluster singles and doubles (CCSD) with different quantum mechanical a…
Which options exist for NISQ-friendly linear response formulations?
Karl Michael Ziems, Erik Rosendahl Kjellgren, Peter Reinholdt +4
Linear response (LR) theory is a powerful tool in classic quantum chemistry crucial to understanding photo-induced processes in chemistry and biology. However, performing simulatio…
Quantum Equation of Motion with Orbital Optimization for Computing Molecular Properties in Near-Term Quantum Computing
Phillip W. K. Jensen, Erik Rosendahl Kjellgren, Peter Reinholdt +4
Determining the properties of molecules and materials is one of the premier applications of quantum computing. A major question in the field is how to use imperfect near-term quant…
The variational quantum eigensolver self-consistent field method within a polarizable embedded framework
Erik Rosendahl Kjellgren, Peter Reinholdt, Aaron Fitzpatrick +6
We formulate and implement the Variational Quantum Eigensolver Self Consistent Field (VQE-SCF) algorithm in combination with polarizable embedding (PE), thereby extending PE to the…
Theoretical and numerical comparison of quantum- and classical embedding models for optical spectra
Marina Jansen, Peter Reinholdt, Erik D. Hedegård +1
Quantum-mechanical (QM) and classical embedding models approximate a supermolecular quantum chemical calculation. This is particularly useful when the supermolecular calculation ha…
Response properties of embedded molecules through the polarizable embedding model
Casper Steinmann, Peter Reinholdt, Morten Steen Nørby +2
The polarizable embedding (PE) model is a fragment-based quantum-classical approach aimed at accurate inclusion of environment effects in quantum-mechanical response property calcu…