Can spin-component scaled MP2 achieve kJ/mol accuracy for cohesive energies of molecular crystals?

TL;DR

This study evaluates the accuracy of spin-component scaled MP2 methods in predicting the cohesive energies of molecular crystals, achieving near kJ/mol precision and improving error margins through parameter optimization.

Contribution

It demonstrates that spin-component scaled MP2 can reach kJ/mol accuracy for molecular crystal energies, with optimized parameters significantly reducing errors.

Findings

MP2 with convergence to the thermodynamic and basis set limits achieves ~1 kJ/mol accuracy.

Standard MP2 has a mean absolute error of 12.9 kJ/mol compared to experiment.

Spin-component scaled MP2 reduces the error to 7.5 kJ/mol with reoptimized parameters.

Abstract

Achieving kJ/mol accuracy in the cohesive energy of molecular crystals, as necessary for crystal structure prediction and the resolution of polymorphism, is an ongoing challenge in computational materials science. Here, we evaluate the performance of second-order M{\o}ller-Plesset perturbation theory (MP2), including its spin-component scaled models, by calculating the cohesive energies of the 23 molecular crystals contained in the X23 dataset. Our calculations are performed with periodic boundary conditions and Brillouin zone sampling, and we converge results to the thermodynamic limit and the complete basis set limit to an accuracy of about 1 kJ/mol (0.25 kcal/mol), which is rarely achieved in previous MP2 calculations of molecular crystals. Comparing to experimental cohesive energies, we find that MP2 has a mean absolute error of 12.9 kJ/mol, which is comparable to that of DFT using the PBE functional and TS dispersion correction. Separate scaling of the opposite-spin and same-spin components of the correlation energy, with parameters previously determined for molecular interactions, reduces the mean absolute error to 9.5 kJ/mol, and reoptimizing the spin-component scaling parameters for the X23 set further reduces the mean absolute error to 7.5 kJ/mol.