Читать книгу Computational Methods in Organometallic Catalysis - Yu Lan - Страница 23

Indeed, there is no unified standard for the classification of density functionals in the physical chemistry field. In 2001, J. P. Perdew et al. proposed using “Jacob's ladder” to classify the level of density functionals [39, 40]. As shown in Scheme 2.1, the ground in the “Jacob's ladder” is HF theory, which is an imprecise method with neither exchange energy nor correlation energy. In fact, HF calculation is rarely used in theoretical and computational chemistry nowadays.

Scheme 2.1 Jacob's ladder of density functionals.

The first rung in “Jacob's ladder” is the density functional based on L(S)DA, the variable in which kind of functionals is the local spin density. The exchange functional of L(S)DA can be written as analytic expressions, which is often called Slater or Dirac exchange functional. However, the correlation functional of L(S)DA has no analytic expression, and can only be fitted by a functional with parameters from the results of high‐level calculations on some uniform electron gases. L(S)DA has achieved surprising success in the early works on the computational study of solid‐state physics. However, it is failure in computational chemistry because L(S)DA usually overestimates the bonding energy.