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Quantum algorithm for obtaining the energy spectrum of molecular systems
Hefeng Wang1, Sabre Kais, Alán Aspuru-Guzik
1Department of Chemistry and Birck Nanotechnolodge Center, Purdue University, West Lafayette, IN 47907, US.
Quantum computers offer efficient molecular energy calculations using a novel algorithm. This approach leverages multiconfigurational self-consistent field (MCSCF) wave functions for improved accuracy and accessibility of excited states.
Area of Science:
- Quantum computing
- Computational chemistry
- Molecular physics
Background:
- Classical computers face exponential scaling challenges for simulating molecular energies via the Schrödinger equation.
- Quantum computing offers polynomial scaling for these simulations, presenting a significant advantage.
Purpose of the Study:
- To present a quantum algorithm for determining molecular energy spectra.
- To utilize multiconfigurational self-consistent field (MCSCF) wave functions for enhanced quantum simulations.
Main Methods:
- Developed a quantum algorithm based on MCSCF wave functions to compute molecular energy spectra.
- Investigated the impact of MCSCF space size on quantum algorithm success probability.
- Suggested a multi-reference configuration interaction approach for larger systems.
Main Results:
- The quantum algorithm successfully obtained the energy spectrum of the water molecule.
- Using MCSCF wave functions as initial guesses grants access to excited states.
- Increased MCSCF space size improved quantum algorithm success probability, even for geometries far from equilibrium.
Conclusions:
- Quantum algorithms utilizing MCSCF wave functions provide a more efficient route to study molecular potential energy surfaces.
- This method enhances the study of excited states and molecular properties compared to simpler approximations.
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