Molecular Electrical Properties from Quantum Monte Carlo Calculations: Application to Ethyne

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Physics

Background:

• Accurate calculation of molecular properties is crucial in chemistry.
• Ethyne (acetylene) is a fundamental molecule with important industrial applications.
• Advanced quantum mechanical methods are needed for precise property prediction.

Purpose of the Study:

• To compute the polarizability and quadrupole moment of ethyne.
• To assess the efficiency and accuracy of the Jastrow-Antisymmetrised Geminal Power (JAGP) wave function.
• To investigate electronic density distributions in ethyne.

Main Methods:

• Utilized Quantum Monte Carlo (QMC) methods.
• Employed the Jastrow-Antisymmetrised Geminal Power (JAGP) wave function.
• Optimized variational parameters and studied basis set convergence.
• Generalized an improved electronic density estimator.

Main Results:

• Achieved fast convergence of electrical properties with basis set size.
• Variational results closely matched Lattice Regularized Diffusion Monte Carlo (LRDMC) values.
• Obtained excellent agreement with experimental data and other quantum chemistry calculations.
• Successfully studied electronic density along C≡C and C-H bonds.

Conclusions:

• The JAGP wave function is a compact and effective ansatz for QMC calculations.
• QMC methods with the JAGP ansatz provide accurate molecular properties for ethyne.
• The generalized electronic density estimator is suitable for molecular systems.