# @method settings

The method settings section defines task-independent parameters for the computational method.

| `backend` <a id="backend"></a> | |
|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Description** | Sets the Integral/SCF backend. The chosen backend affects only the SCF part of the calculation. Penguin itself is entirely agnostic to the chosen backend. |
| **Type**        | str |
| **Default**     | vlx |
| **Options**     | <strong>vlx</strong> sets <strong>VeloxChem</strong> as the used backend<br><strong>pyscf</strong> sets <strong>PySCF</strong> as the used backend |

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| `basis` <a id="basis"></a> | |
|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Description** | Specifies the basis set to be used in the calculation. |
| **Type**        | str |
| **Default**     | None |
| **Options**     | The available basis sets depend on the chosen integral/SCF backend<br>We refer to the documentation of the [`backend`](#backend) for the list of supported basis sets |

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| `auxbasis` <a id="auxbasis"></a> | |
|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Description** | Sets the auxiliary basis set used in the calculation. Used for methods requiring auxiliary basis sets, such as density fitting. |
| **Type**        | str |
| **Default**     | None |
| **Availability** | Only relevant for the <strong>pyscf<strong> [`backend`](#backend) |
| **Options**     | The available auxiliary basis sets depend on the chosen integral/SCF backend<br>We refer to the documentation of the [`backend`](#backend) for the list of supported auxiliary basis sets |