13.5 The Nuclear-electronic Orbital (NEO) Approach: Integrating Electronic and Nuclear Quantum Effects in Quantum Chemistry

13.5.5 Examples

(June 30, 2021)

Example 13.7  Input for the NEO-HF calculation on H2O molecule with the second proton treated quantum-mechanically. The electronic basis set is cc-pVDZ and the protonic is an uncontracted 2s2p2d basis set with exponents 4.0 and 8.0.

$molecule
   0 1
   H   -3.5008791    1.2736107    0.7596000
   O   -3.9840791    1.3301107   -0.0574000
   H   -4.9109791    1.2967107    0.1521000
$end

$rem
   METHOD   hf
   BASIS    cc-pvdz
   NEO      true
$end

$neo_basis
H    3
S    1    1.000000
   4.0 1.0
S    1    1.000000
   8.0 1.0
P    1    1.000000
   4.0 1.0
P    1    1.000000
   8.0 1.0
D    1    1.000000
   4.0 1.0
D    1    1.000000
   8.0 1.0
****
$end

View output

Example 13.8  Input for the NEO-DFT-epc172 geometry optimization calculation of all centers on CH2O molecule with both protons treated quantum-mechanically. The electronic exchange-correlation functional is PBE0. The electronic basis set is STO-3G and the protonic is an uncontracted 1s1p basis set with exponents 4.0. This calculation utilizes DFT grid with 99 radial and 302 spherical quadrature points along with the DIIS algorithm.

$molecule
   0 1
   C     0.000000    0.000000    0.000000
   O     0.000000    0.000000    1.220000
   H     0.935307    0.000000   -0.540000
   H    -0.935307    0.000000   -0.540000
$end

$rem
   JOBTYPE           OPT
   METHOD            pbe0
   BASIS             sto-3g
   NEO               true
   NEO_EPC           epc172
   SYM_IGNORE        1
   SCF_CONVERGENCE   11
   MAX_SCF_CYCLES    100
   SCF_ALGORITHM     diis
   XC_GRID           000099000302
$end

$neo_basis
H    3
S    1    1.000000
   4.0 1.0
P    1    1.000000
   4.0 1.0
****
H    4
S    1    1.000000
   4.0 1.0
P    1    1.000000
   4.0 1.0
****
$end

View output

Example 13.9  Input for the NEO-DFT-epc19 geometry optimization calculation of the NEO center only on open-shell OH radical molecule with a proton treated quantum-mechanically. The electronic exchange-correlation functional is PBE0. The electronic basis set is 6-31G and the protonic is an uncontracted 1s1p basis set with exponents 4.0. This calculation utilizes DFT grid with 99 radial and 230 spherical quadrature points along with the DIIS algorithm.

$molecule
   0 2
   O    -4.511414   1.264878   0.000000
   H    -2.739325   1.866123   0.000000
$end

$rem
   JOBTYPE           OPT
   METHOD            pbe0
   BASIS             6-31g
   UNRESTRICTED      true
   INPUT_BOHR        true
   NEO               true
   SYM_IGNORE        1
   SCF_CONVERGENCE   6
   MAX_SCF_CYCLES    100
   SCF_ALGORITHM     diis
   NEO_EPC           epc19
   XC_GRID           000099000230
$end

$opt
   FIXED
   1 XYZ
   ENDFIXED
$end

$neo_basis
H    2
S    1    1.000000
   4.0 1.0
P    1    1.000000
   4.0 1.0
****
$end

View output

Example 13.10  Input for the NEO-TDDFT-epc19 calculation on CH2O molecule (both protons treated quantum-mechanically) of the first five roots obtained with the Davidson algorithm. The electronic exchange-correlation functional is PBE0. The electronic basis set is STO-3G and the protonic is an uncontracted 1s1p basis set with exponents 4.0. This calculation utilizes DFT grid with 99 radial and 302 spherical quadrature points.

$molecule
   0 1
   C     0.000000    0.000000    0.000000
   O     0.000000    0.000000    1.220000
   H     0.935307    0.000000   -0.540000
   H    -0.935307    0.000000   -0.540000
$end

$rem
   METHOD            pbe0
   BASIS             sto-3g
   THRESH            14
   XC_GRID           000099000302
   S2THRESH          12
   NEO               true
   NEO_EPC           epc172
   SET_ROOTS         5
   RPA               true
   SCF_CONVERGENCE   12
   NEO_E_CONV        12
$end

$neo_basis
H    3
S    1    1.000000
   4.0 1.0
P    1    1.000000
   4.0 1.0
****
H    4
S    1    1.000000
   4.0 1.0
P    1    1.000000
   4.0 1.0
****
$end

View output

Example 13.11  Input for the NEO-TDHF calculation on the FDF- molecule treating quantum nuclei as deuterium and employing NO_VPP option. The electronic basis set is cc-pVDZ and the protonic is an uncontracted even-tempered 8s8p basis set.

$molecule
   -1 1
   F   0.000000   0.000000   -1.122987
   F   0.000000   0.000000    1.122987
   H   0.000000   0.000000    0.000000
$end

$rem
   METHOD            hf
   BASIS             cc-pvdz
   NEO               true
   SCF_ALGORITHM     GDM
   RPA               true
   CIS_N_ROOTS       100
   THRESH            14
   S2THRESH          12
   SCF_CONVERGENCE   11
   MAX_SCF_CYCLES    300
   NEO_VPP           0
   NEO_ISOTOPE       2
   NEO_E_CONV        11
$end

$neo_basis
H    3
S    1    1.000000
   2.828400 1.0
S    1    1.000000
   4.0 1.0
S    1    1.000000
   5.6569 1.0
S    1    1.000000
   8.0 1.0
S    1    1.000000
   11.3137 1.0
S    1    1.000000
   16.0 1.0
S    1    1.000000
   22.6274 1.0
S    1    1.000000
   32.0 1.0
P    1    1.000000
   2.828400 1.0
P    1    1.000000
   4.0 1.0
P    1    1.000000
   5.6569 1.0
P    1    1.000000
   8.0 1.0
P    1    1.000000
   11.3137 1.0
P    1    1.000000
   16.0 1.0
P    1    1.000000
   22.6274 1.0
P    1    1.000000
   32.0 1.0
****
$end

View output