# S02

Standard

```S02 s02
```

The S02 card specifies the amplitude reduction factor $S^2_0$ . If the entry for $S^2_0$ is less than 0.1, then the value of $S^2_0$ is estimated from atomic overlap integrals. Experimental values of $S^2_0$ are typically between 0.8 and 1.0.

Alternatively, you can specify the value of $S^2_0$ in the HOLE or EDGE card; however, the meaning of the parameters in the ‘feff.inp’ file is more clear if you use the S02 card.

```* let FEFF calculate S02
S02 0.0
```