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What is the difference between PBE and PBEsol exchange–correlation functionals?

In my computational materials science work, selecting the right functional is critical for accuracy. The literature mentions both, but the nuanced difference in their parameterization and best-use cases isn't always clear for applied research.

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By Rishabh Khanna Answered 3 years ago

In practice, the choice hinges on whether you prioritize general molecular properties or precise solid-state lattice parameters. PBE, the original, is a robust general-purpose functional but tends to overestimate lattice constants. PBEsol, which I've used extensively for ceramics and perovskites, reparameterizes PBE to satisfy the gradient expansion for solids, dramatically improving equilibrium properties like lattice geometry and bulk moduli. For surface energies or cohesive energies in solids, I would recommend PBEsol. Stick with standard PBE for broader molecular sets.

 

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