Density Matrix Embedding Using Multiconfiguration Pair-Density Functional Theory.

Area of Science:

• Quantum chemistry
• Materials science
• Computational physics

Background:

• Accurate simulation of extended systems is computationally demanding.
• Quantum embedding methods offer a way to treat complex electronic structures efficiently.
• Multiconfiguration pair-density functional theory (MC-PDFT) is a powerful but costly method for electronic structure calculations.

Purpose of the Study:

• To present a novel quantum embedding method for ground and excited states of extended systems.
• To enable accurate calculations of local excitations in materials with defects.
• To reduce the computational cost associated with traditional MC-PDFT for large systems.

Main Methods:

• Integration of multiconfiguration pair-density functional theory (MC-PDFT) with periodic density matrix embedding theory (pDMET).
• The combined method is denoted as pDME-PDFT.
• Application to calculate local excitations in oxygen mono- and divacancies on a magnesium oxide (100) surface.

Main Results:

• The pDME-PDFT method achieves high accuracy, with absolute deviations within 0.05 eV compared to nonembedded MC-PDFT for local excitations.
• Demonstrated the efficiency of pDME-PDFT for larger supercells, where nonembedded MC-PDFT is computationally prohibitive.
• Successfully calculated local excitations in oxygen vacancies within a magnesium oxide surface.

Conclusions:

• The pDME-PDFT method provides a computationally efficient and accurate approach for studying electronic excitations in extended systems with defects.
• This method significantly lowers the barrier for applying advanced quantum chemistry techniques to complex material surfaces.
• The findings pave the way for more detailed investigations of defect properties in functional materials.