1993 (Becke)  : Hybrid Functionals

Axel D. Becke introduced the adiabatic-connection model, which allows for mixing of DFT exchange and Fock-like exchange via the formula $$ E_{\text{x}} = a \cdot E^{\text{HF}}_x + b \cdot E^{\text{GGA}}_x $$ to obtain the exchange part of the exchange-correlation energy. Typically, one imposes $a+b = 1$, but some authors have sometimes abandoned the summation to $1$ or introduced exchange from the local density approximation (LDA a.k.a. Slater-Exchange) to the mix (B3LYP falls into this category).

Hybrids show improved performance over GGAs and meta-GGAs for the HOMO-LUMO gap, thermochemistry and excited states via time-dependent DFT. Especially for the latter, mixing parameters that are dependent on the electron-electron distance have yielded good results, leading to "long-range corrected" or "range-separated" hybrid functionals such as LC-PBE.

Technically, this is not more recent than 1996. Given the impact of hybrid functionals, I think it is proper to list this milestone regardless.

1993 (Becke): Hybrid Functionals

Axel D. Becke introduced the adiabatic-connection model, which allows for mixing of DFT exchange and Fock-like exchange via the formula $$ E_{\text{x}} = a \cdot E^{\text{HF}}_x + b \cdot E^{\text{GGA}}_x $$ to obtain the exchange part of the exchange-correlation energy. Typically, one imposes $a+b = 1$, but some authors have sometimes abandoned the summation to $1$ or introduced exchange from the local density approximation (LDA a.k.a. Slater-Exchange) to the mix (B3LYP falls into this category).

Hybrids show improved performance over GGAs and meta-GGAs for the HOMO-LUMO gap, thermochemistry and excited states via time-dependent DFT. Especially for the latter, mixing parameters that are dependent on the electron-electron distance have yielded good results, leading to "long-range corrected" or "range-separated" hybrid functionals such as LC-PBE.

1993 (Becke) Hybrid Functionals

Axel D. Becke introduced the adiabatic-connection model, which allows for mixing of DFT exchange and Fock-like exchange via the formula $$ E_{\text{x}} = a \cdot E^{\text{HF}}_x + b \cdot E^{\text{GGA}}_x $$ to obtain the exchange part of the exchange-correlation energy. Typically, one imposes $a+b = 1$, but some authors have sometimes abandoned the summation to $1$ or introduced exchange from the local density approximation (LDA a.k.a. Slater-Exchange) to the mix (B3LYP falls into this category).

Hybrids show improved performance over GGAs and meta-GGAs for the HOMO-LUMO gap, thermochemistry and excited states via time-dependent DFT. Especially for the latter, mixing parameters that are dependent on the electron-electron distance have yielded good results, leading to "long-range corrected" or "range-separated" hybrid functionals such as LC-PBE.

Technically, this is not more recent than 1996. Given the impact of hybrid functionals, I think it is proper to list this milestone regardless.

1993 (Becke) : Hybrid Functionals

Axel D. Becke introduced the adiabatic-connection model, which allows for mixing of DFT exchange and Fock-like exchange via the formula $$ E_{\text{x}} = a \cdot E^{\text{HF}}_x + b \cdot E^{\text{GGA}}_x $$ to obtain the exchange part of the exchange-correlation energy. Typically, one imposes $a+b = 1$, but some authors have sometimes abandoned the summation to $1$ or introduced exchange from the local density approximation (LDA a.k.a. Slater-Exchange) to the mix (B3LYP falls into this category).

Hybrids show improved performance over GGAs and meta-GGAs for the HOMO-LUMO gap, thermochemistry and excited states via time-dependent DFT. Especially for the latter, mixing parameters that are dependent on the electron-electron distance have yielded good results, leading to "long-range corrected" or "range-separated" hybrid functionals such as LC-PBE.

Technically, this is not more recent than 1996. Given the impact of hybrid functionals, I think it is proper to list this milestone regardless.