## dft-kernel

Set details of the DFT kernel.

**Input block**

**Short variant**

```
dft-kernel:
[functional]
```

**Extended variant**

`dft-kernel:`

`skip: [boolean]`

`type: [formatted-string]`

`functional: [functional]`

**Default**

```
dft-kernel:
functional : from-scf
type : analytical
skip : false
```

**Example**

```
dft-kernel:
functional : ALDA
type : analytical
```

### Warning

- The use of skip, ALDA and XLADA options is not recommended, since they approximate the full DFT kernel. Their use is only recommended when comparing the calculated data to the implementation in other QCh codes, where these approximations can not be avoided.

## eri

Specify details associated with the evaluation of electron repulsion integrals (ERI) and related two-electron Fock contributions.

## analysis

Analyze contributions from molecular orbitals to the paramagnetic part of the NMR shielding tensor.

**Input block**

**Short variant**

```
analysis:
[analyze]
```

**Extended variant**

`analysis:`

`analyze: [analyze]`

`xyz-values: [string]`

`sort: [boolean]`

`occ-threshold: [real]`

`vir-threshold: [real]`

`energy-degeneracy: [real]`

`output-digits: [integer]`

`fix-occ-orbital: [integer]`

`fix-vir-orbital: [integer]`

**Default**

```
analysis:
analyze : none
xyz-values : principal
sort : True
occ-threshold : 0.1
vir-threshold : 0.1
energy-degeneracy : 1.0e-8
output-digits : 2
fix-occ-orbital : 0
fix-vir-orbital : 0
```

**Example**

```
analysis:
analyze : MO
xyz-values : diagonal
sort : False
occ-threshold : 0.01
vir-threshold : 0.01
```

## g-factor

Specify the nuclear g-factor.

**Input block**

**Extended variant**

`g-factor:`

`[element-symbol]: [integer]`

`[element-index]: [integer]`

`...`

**Default**

`G-factor of isotopes with largest abundance and non-zero spin.`

**Example**

```
g-factor:
H : 5.5856947
2 : 0.8574382
C : 1.4048236
```

### Note

- Although NMR shielding tensor is calculated only for elements with non-zero g-factor (see Tip below), the actual result does not depend on the g-factor value.

- The data in the g-factor block is processed line by line, therefore the latter data overwrites the former one.

- Data from g-factor block overwrites setting from the isotope block.

### Tip

- NMR shielding tensor is calculated only for NMR active atoms (non-zero g-factor). This keyword can be used to set non-zero g-factor for elements witch isotopes have only zero or unknown magnetic moment to perform hypothetical studies (like f.e. At).

## grid

Specify atomic grids for the numerical evaluation of exchange-correlation DFT contributions.

**Input block**

**Short variant**

```
grid:
[grid-type]
```

**Extended variant**

`grid:`

`all: [string]`

`[element-symbol]: [string]`

`[element-index]: [string]`

`...`

**Default**

`Grid is taken from scf part of the calculation.`

**Example**

`grid: large`

```
grid:
C: medium
7: large
```

### Note

- There can be multiple instances of element-symbol and element-index in the grid block.

- While lines in the grid block can be mixed, they are always processed in the following order: "all", all "element-symbol" and all "element-index" keywords.

- The order of processing the data matters, since the latter lines rewrite the data of the former lines. This way one can easily set the same grid for all Carbons except the Carbon number 7 (see example).

## auxbas

Specify atomic auxiliary basis sets.

**Input block**

**Short variant**

```
auxbas:
[basis-name]
```

**Extended variant**

`auxbas:`

`all: [basis-name]`

`[element-symbol]: [basis-name]`

`[element-index]: [basis-name]`

`...`

**Default**

`none`

**Example**

In this example, auxiliary ucc-pvtz basis is assigned to all elements.

`auxbas: ucc-pvtz`

In this example, upc-2 basis is assigned to the 4th element (as specified in the input block "geometry") and dyall-vtz basis to all bromine atoms.

```
auxbas:
4: upc-2
Br: dyall-vtz
```

### Note

- The use of auxiliary basis makes sense only in connection with an approximative evaluation of electron repulsion integrals (ERI) by means of the resolution-of-identity (RI) technique. This is controlled by the keyword "acceleration" in the "eri" block.

- In the case of missing definition of auxiliary basis, the program will assign the basis automatically based on the chosen orbital basis, provided the orbital basis was selected from the internal program library.

## gauge

Options for solving the gauge origin problem.

**Input line****Default**

```
gauge:
[formatted-string]
```

`gauge: giao`

**Example**

`gauge: atom 2`

`gauge: center-of-mass`

## active-atoms

Specify atoms for the calculation of NMR shielding tensor.

**Input line****Default**

```
active-atoms:
[formatted-string]
```

`active-atoms: all`

**Example**

`active-atoms: H`

`active-atoms: 5, C, 1-3`

## convergence

Convergence threshold for the self-consistent procedure.

**Input line****Default**

```
convergence:
[real]
```

`convergence: 1.0e-5`

**Example**

`convergence: 1.0e-3`

## dmixing

Mixing parameter for the self-consistent procedure.

**Input line****Default**

```
dmixing:
[real]
```

`dmixing: 1.0e0`

**Example**

`dmixing: 0.2e0`

## maxiterations

Maximum number of iterations for the self-consistent procedure.

**Input line****Default**

```
maxiterations:
[integer]
```

`maxiterations: 30`

**Example**

`maxiterations: 20`

## magnetic-field

Orientation of the external magnetic field perturbation.

## response-only

It allows to calculate only response molecular orbitals.

**Input line****Default**

```
response-only:
[boolean]
```

`response-only: False`

**Example**

`response-only: True`

### Tip

- Combine keywords response-only and magnetic-field to speed up calculation, if you are (f.e.) interested only in the visualization of certain component of magnetically induced current density.

## spin-orbit

Calculate the spin-orbit contribution to the non-relativistic NMR shielding tensor within CGO method. This keyword is recommended to use only in conjunction with "analysis" keyword (see the Warning message).

**Input line****Default**

```
spin-orbit:
[boolean]
```

`spin-orbit: False`

**Example**

`spin-orbit: True`

### Warning

- The purpose of this keyword is to perform molecular orbital analysis of the spin-orbit contribution to the paramagnetic part of the NMR shielding tensor. It is NOT recommended to use it for practical calculations since it captures only portion of relativistic effects and does not accommodate London atomic orbitals.

## Latest Publications

### All-electron fully relativistic Kohn-Sham theory for solids based on the Dirac-Coulomb Hamiltonian and Gaussian-type functions

### Electron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems

## Useful Links

## Our Contacts

Department of Chemistry

UiT The Arctic University of Norway

Tromsø, NO-9037 Norway

Email: info@respectprogram.eu