  Recently, Tao and Mo (TM) proposed an accurate all-purpose nonempirical
meta-generalized gradient approximation (meta-GGA). The exchange part was
derived from the density matrix approximation, while the correlation part is
based on a modification of TPSS correlation in the low-density or
strong-interaction limit. To further understand this density functional, we
combine the TM exchange part with the original TPSS correlation and make a
comprehensive assessment of this combination, which we call TMTPSS functional,
on solids and solid surfaces. Our test includes 22 lattice constants and bulk
moduli, 30 band gaps of semiconductors, 7 cohesive energies, and surface
exchange-correlation energies for rs ranging from 2 to 3 bohr. Our calculations
show that TMTPSS functional is quite competitive to the TM meta-GGA functional,
improving upon the nonempirical functionals LSDA, PBE GGA, and TPSS meta-GGA
for most properties considered. In particular, it significantly improves the
surface exchange-correlation energy calculation, with a mean absolute error of
only 1 erg/cm2.
