# CCDENSITY

Computes the coupled cluster density matrices. Called whenever CC properties and/or gradients are required.

## General

### AO_BASIS

> The algorithm to use for the \(\left\langle VV||VV\right \rangle\) terms

> - Type: string
> - Possible Values: NONE, DISK, DIRECT
> - Default: NONE

### CACHELEVEL

> The amount of caching of data to perform

> - Type: integer
> - Default: 2

### DEBUG

> Reproducing energies from densities ?

> - Type: integer
> - Default: 0

### GAUGE

> The type of gauge to use for properties

> - Type: string
> - Default: LENGTH

### INTS_TOLERANCE

> Schwarz screening threshold. Mininum absolute value below which TEI are neglected.

> - Type: conv double
> - Default: 1e-14

### ONEPDM

> Do compute one-particle density matrix?

> - Type: boolean
> - Default: false

### ONEPDM_GRID_CUTOFF

> Cutoff (e/A^3) for printing one-particle density matrix values on a grid

> - Type: double
> - Default: 1.0e-30

### ONEPDM_GRID_DUMP

> Write one-particle density matrix on a grid to file opdm.dx

> - Type: boolean
> - Default: false

### ONEPDM_GRID_STEPSIZE

> Step size (Angstrom) for one-particle density matrix values on a grid

> - Type: double
> - Default: 0.1

### OPDM_RELAX

> Do relax the one-particle density matrix?

> - Type: boolean
> - Default: false

### PROP_ALL

> Compute non-relaxed properties for all excited states.

> - Type: boolean
> - Default: true

### PROP_ROOT

> Root number (within its irrep) for computing properties

> - Type: integer
> - Default: 1

### PROP_SYM

> The symmetry of states

> - Type: integer
> - Default: 1

### REFERENCE

> Reference wavefunction type

> - Type: string
> - Default: RHF

### ROOTS_PER_IRREP

> The number of electronic states to computed, per irreducible representation

> - Type: array
> - Default: No Default

### WRITE_NOS

> Do write natural orbitals (molden)

> - Type: boolean
> - Default: false

### XI

> Do compute Xi?

> - Type: boolean
> - Default: false

### ZETA

> Do use zeta?

> - Type: boolean
> - Default: false

## Expert

### AEL

> Do compute the approximate excitation level? See Stanton and Bartlett, JCP, 98, 1993, 7034.

> - Type: boolean
> - Default: false

### WFN

> Wavefunction type

> - Type: string
> - Default: SCF

### XI_CONNECT

> Do require \(\bar{H}\) and \(R\) to be connected?

> - Type: boolean
> - Default: false