# *DFT¶

**Introduction**¶

In this link the directives for modifying the DFT calculation are described (e.g. modifying grid, using ALDA and much more)

*typical input (here correcting LDA):*

```
**HAMILTONIAN
.DFT
LDA
*DFT
.SAOP
LBalpha
```

Single line following .SAOP : asymptotic potential (currently LB94 or LBalpha).

The specification of the functional is described in connection with the .DFT
option in the *.DFT* section

The DFT module is described in references [Schipper2000], [Saue2002], [Fossgaard2003].

It uses standard non-relativistic functionals. This is justified in many cases since various studies, like refs. [Varga1999], [Varga2000], [Mayer1996], indicate that relativistic corrections to the exchange-correlation functionals have a negligible effect on spectroscopic constants; however, for example for core properties further studies are necessary.

**Integration algorithm and thresholds**¶

### .SCREENING¶

Specify the screening threshold used in the BLAS-3 integration scheme.

*Default:*

```
.SCREENING
1.0D-18
```

### .POINTWISE¶

Switch to old (unscreened) BLAS-2 integration scheme (default before DIRAC11) instead of the new BLAS-3 scheme (default since DIRAC11).

### .TINYDENS¶

Specify the tiny density threshold. Grid points with a density smaller than this threshold do not contribute to XC matrix elements.

*Default:*

```
.TINYDENS
1.0D-14
```

**Asymptotic correction**¶

### .GRAC¶

Activate the gradient regulated asymptotic correction scheme (GRAC), [Gruning2001], followed by two lines of input.

First line: Asymptotic potential (currently LB94 or LBalpha).

Second line (free format): Parameters α and β (see reference [Gruning2001]) the ionization potential, and the threshold for difference in HOMO eigenvalue below which asymptotic correction is switched on. A sufficiently converged density is needed before the correction is activated (before the bulk potential is shifted in order to reproduce the desired IP (see reference [Gruning2001])

*Typical input (here correcting PBE0):*

```
**HAMILTONIAN
.DFT
PBE0
*DFT
.GRAC
LB94
0.5 40.0 0.79248 1.0D-6
```

### .SAOP!¶

Activate the statistical averaging of (model) orbital potentials (SAOP)
as defined in reference [Schipper2000].
This implies (and
activates) the ALDA kernel. The functional under *.DFT* is expected to be
GLLBhole. The asymptotic potential is LBalpha.

*Recommended input:*

```
**HAMILTONIAN
.DFT
GLLBhole
*DFT
.SAOP!
```

**Spin magnetization TDDFT**¶

### .NOSAOP¶

Turn off spin density contribution to XC response.

### .COLLINEAR¶

Use the collinear approximation as a definition of the spin density.

instead of the default noncollinear definition

### .BETASIGMA¶

use

instead of the default form

**Adiabatic local density approximation (ALDA)**¶

### .ALDA¶

Approximate all functional derivatives beyond the xc potential by SVWN derivatives. For hybrid functionals exact exchange is switched off in the solution of the response equation.

### .ALDA+¶

Use *.ALDA+* only for the Hermitian contribution (density
contribution) and use the proper xc kernel for the anti-Hermitian part
(spin density contribution).

### .ALDA-¶

Use *.ALDA-* only for the anti-Hermitian contribution (spin
density contribution) and use the proper xc kernel for the Hermitian
part (density contribution).

**Other functionality**¶

### .GAUNTSCALE¶

Scale Gaunt integrals (if included) with the same factor as for
Hartree-Fock exchange. This means that hybrid functionals include
fractional HF Gaunt interaction, and pure functionals no HF Gaunt
interaction at all. If this option is not given the Gaunt integrals will
be included to 100%, meaning that even an LDA calculation will include
full Hartree-Fock Gaunt interaction when the .GAUNT keyword is given in
***HAMILTONIAN*.

### .OVLDIAG¶

Activate the overlap diagnostic for TD-DFT calculations of excitation energies according to [Peach2008]. This is only available in the development version.