6.22 Variational Two-Electron Reduced-Density-Matrix Methods

6.22.4 Examples

(May 16, 2021)

Example 6.50  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                           sto-3g
    AUX_BASIS                       rimp2-vdz
    METHOD                          rdm
    UNRESTRICTED                    false
    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
$end

View output

Example 6.51  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
    JOBTYPE                         sp
    BASIS                           sto-3g
    AUX_BASIS                       rimp2-vdz
    METHOD                          rdm
    UNRESTRICTED                    false
    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
$end

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

View output

Example 6.52  Single-point v2RDM-CASSCF/cc-pVDZ energy and gradient 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
    JOBTYPE                         force
    BASIS                           cc-pvdz
    AUX_BASIS                       rimp2-cc-pvdz
    METHOD                          rdm
    UNRESTRICTED                    false
    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_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

View output