6.18 Variational Two-Electron Reduced-Density-Matrix Methods

6.18.4 Examples

Example 6.34  Single-point v2RDM/STO-3G energy computation.

$molecule
    0 1
    O  0.0000  0.0000  0.1173
    H  0.0000  0.7572 -0.4692
    H  0.0000 -0.7572 -0.4692
$end

$rem
    BASIS                           cc-pvdz
    METHOD                          rdm
    UNRESTRICTED                    false
    RDM_SOLVER                      vector
    RDM_POSITIVITY                  dqg
    RDM_CONSTRAIN_SPIN              true
    RDM_MU_UPDATE_FREQUENCY         200
    RDM_EPS_CONVERGENCE             4
    RDM_E_CONVERGENCE               4
    RDM_MAXITER                     500000
    RDM_TAU                         10
    RDM_PRINT                       1
    RDM_OPTIMIZE_ORBITALS           true
    RDM_ORBOPT_ENERGY_CONVERGENCE   7
    RDM_ORBOPT_GRADIENT_CONVERGENCE 4
    RDM_ORBOPT_FREQUENCY            500
    RDM_ORBOPT_MAXITER              5
$end

$rdm_active_space
¯0 0 0 0 ! frozen orbitals
¯1 0 0 0 ! restricted orbitals
¯3 0 2 1 ! active orbitals
$end

Example 6.35  Single-point v2RDM/STO-3G energy computation with frozen core orbital.

$molecule
    0 1
    O  0.0000  0.0000  0.1173
    H  0.0000  0.7572 -0.4692
    H  0.0000 -0.7572 -0.4692
$end

$rem
    BASIS                           cc-pvdz
    METHOD                          rdm
    UNRESTRICTED                    false
    RDM_SOLVER                      vector
    RDM_POSITIVITY                  dqg
    RDM_CONSTRAIN_SPIN              true
    RDM_MU_UPDATE_FREQUENCY         200
    RDM_EPS_CONVERGENCE             4
    RDM_E_CONVERGENCE               4
    RDM_MAXITER                     500000
    RDM_TAU                         10
    RDM_PRINT                       1
    RDM_OPTIMIZE_ORBITALS           true
    RDM_ORBOPT_ENERGY_CONVERGENCE   7
    RDM_ORBOPT_GRADIENT_CONVERGENCE 4
    RDM_ORBOPT_FREQUENCY            500
    RDM_ORBOPT_MAXITER              5
$end

$rdm_active_space
¯0 0 0 0 ! frozen orbitals
¯1 0 0 0 ! restricted orbitals
¯3 0 2 1 ! active orbitals
$end

Example 6.36  Single-point v2RDM-CASSCF/cc-pVDZ energy computation.

$molecule
    0 1
    O  0.0000  0.0000  0.1173
    H  0.0000  0.7572 -0.4692
    H  0.0000 -0.7572 -0.4692
$end

$rem
    BASIS                           cc-pvdz
    METHOD                          rdm
    UNRESTRICTED                    false
    RDM_SOLVER                      vector
    RDM_POSITIVITY                  dqg
    RDM_CONSTRAIN_SPIN              true
    RDM_MU_UPDATE_FREQUENCY         200
    RDM_EPS_CONVERGENCE             4
    RDM_E_CONVERGENCE               4
    RDM_MAXITER                     500000
    RDM_TAU                         10
    RDM_PRINT                       1
    RDM_OPTIMIZE_ORBITALS           true
    RDM_ORBOPT_ENERGY_CONVERGENCE   7
    RDM_ORBOPT_GRADIENT_CONVERGENCE 4
    RDM_ORBOPT_FREQUENCY            500
    RDM_ORBOPT_MAXITER              5
$end

$rdm_active_space
¯0 0 0 0 ! frozen orbitals
¯1 0 0 0 ! restricted orbitals
¯3 0 2 1 ! active orbitals
$end