Quantum computing applied to calculations of molecular energies: CH2 benchmark

Area of Science:

• Quantum computing
• Computational chemistry
• Quantum algorithms

Background:

• Classical computers face exponential scaling challenges for Full Configuration Interaction (FCI) energy calculations.
• Quantum computers promise polynomial scaling for FCI, enabling more complex simulations.
• Molecules with multireference character, like CH2, present specific challenges for electronic structure calculations.

Purpose of the Study:

• To develop and implement a quantum Full Configuration Interaction (FCI) algorithm.
• To assess the performance of the quantum FCI algorithm on a benchmark molecular system.
• To investigate the applicability of quantum algorithms to challenging electronic structure problems.

Main Methods:

• Development of a quantum computer simulation code.
• Implementation of a quantum FCI algorithm.
• Performance assessment using the CH2 molecule's four lowest electronic states.

Main Results:

• The quantum FCI algorithm was successfully implemented and tested.
• Performance was evaluated on the CH2 molecule, a known benchmark for multireference character.
• Successful achievement of the probability amplification regime was demonstrated with a tailored initial quantum state.

Conclusions:

• Quantum computing provides a viable alternative for high-accuracy electronic structure calculations.
• The developed quantum FCI algorithm shows promise for tackling complex chemical systems.
• The study validates the potential of quantum algorithms for solving challenging problems in computational chemistry.