### Navigation

- index
- modules
- toc
- next
- previous
- PSI4 [beta5] »
- Appendices »
- Keywords by Module »
- MRCC »

# MRCC_NUM_SINGLET_ROOTS

> Number of singlet roots. (Strictly speaking number of of roots with M_s=0 and S is even.) Use this option only with closed shell reference determinant, it must be zero otherwise. This becomes `nsing` (option #2) in fort.56.

> - Type: integer
> - Default: 1

### Navigation

- index
- modules
- toc
- next
- previous
- PSI4 [beta5] »
- Appendices »
- Keywords by Module »
- MRCC »