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Nonequivalence of the generalized gradient approximations PBE and PW91 Ann E. Mattsson,1,
 

Summary: Nonequivalence of the generalized gradient approximations PBE and PW91
Ann E. Mattsson,1,
* Rickard Armiento,2, Peter A. Schultz,1, and Thomas R. Mattsson3,
1Multiscale Computational Materials Methods, MS 1110, Sandia National Laboratories,
Albuquerque, New Mexico 87185-1110, USA
2
Department of Physics, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm, Sweden
3HEDP Theory/ICF Target Design, MS 1186, Sandia National Laboratories, Albuquerque, New Mexico 87185-1186, USA
Received 20 September 2005; revised manuscript received 20 December 2005; published 30 May 2006
Two of the most popular generalized gradient approximations used in the applications of the density func-
tional theory, PW91 and PBE, are generally regarded as essentially equivalent. They produce similar numerical
results for many simple properties, such as lattice constants, bulk moduli, and atomization energies. We
examine more complex properties of systems with electronic surface regions, with the specific application of
the monovacancy formation energies of Pt and Al. A surprisingly large and consistent discrepancy between
PBE and PW91 results is obtained. This shows that despite similarities found between some simple material
properties, PBE and PW91 are not equivalent. The differences obtained for the monovacancy formation
energies are related to differences in surface intrinsic errors which are substantiated using the idealized,
well-controlled, jellium surface model. In view of the differences obtained with the PW91 and PBE functionals
we develop separate surface intrinsic error corrections for these and revisit some earlier results.
DOI: 10.1103/PhysRevB.73.195123 PACS number s : 71.15.Mb, 61.72.Ji, 73.90. f

  

Source: Armiento, Rickard - Department of Physics, Royal Institute of Technology (KTH)

 

Collections: Materials Science; Physics