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11 Geometry optimization

Geometry optimizations are invoked by the optg input directive, which must follow the input of the method for which the optimization is to be performed. For instance, optimization of the geometry for formaldehyde at the MP2 level is performed with the following input

***,formaldehyde
print,basis,orbitals   !this is optional: print the basis set and the
                       !occupied orbitals
angstrom
geometry={             !define the nuclear coordinates
C
O  , C , rco
H1 , C , rch , O , hco
H2 , C , rch , O , hco , H1 , 180
}

rco=1.182 Ang
rch=1.102 Ang
hco=122.1789 Degree

basis=vdz              !Select basis set
hf                     !Perform HF calculation
mp2                    !Perform MP2 calculation
optg                   !Optimize geometry for MP2

Optimizations use analytical energy gradients if available; otherwise the gradients are computed by finite differences. Presently, analytical energy gradients are available for the following methods.

hf
Closed and open-shell spin restricted Hartree-Fock (RHF)
uhf
Spin-unrestricted Hartree-Fock (UHF).
ks
Spin-restricted closed and open-shell Kohn-Sham calculations.
uks
Spin-unrestricted Kohn-Sham calculations.
mcscf
MCSCF and CASSCF, including state-averaged calculations
mp2
closed-shell MP2
df-mp2
closed-shell MP2 with density fitting
lmp2
closed-shell local MP2
df-lmp2
closed-shell local MP2
ccsd
closed-shell quadratic configuration
ccsd
closed-shell asingles and doubles coupled-cluster
qcisd(t)
closed-shell quadratic configuration, including triples interaction, including perturbative triple-excitation contribution
rs2
Second-order multireference perturbation theory, including multi-state treatments

Various options are available for modifying the convergence thresholds and the optimization method. For details see the reference manual.



Next: 12 Frequency calculations Up: Getting Started with Molpro Previous: 10 Density functional calculations   Contents   PDF

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molpro@molpro.net 2017-12-14