MOLPRO

47 POTENTIAL ENERGY SURFACES (SURF) 356
1D: CCSD(T)/cc-pVTZ
2D: MP4(SDQ)/cc-pVTZ
3D: MP4(SDQ)/cc-pVTZ
{SURF,Start1D=label1
VMULT,Start2D=label2,Start3D=label2,Multi=3}
MULTI=4: The 1D calculation provides all information for the 2D
potential but does not so for the 3D part. Hence, the 1D contribution
and the 2D contributions need to be computed twice. Examples:
1D: CCSD(T)/cc-pVTZ
2D: CCSD(T)/cc-pVTZ
3D: MP4(SDQ)/cc-pVTZ
{SURF,Start1D=label1
VMULT,Start2D=label1,Start3D=label2,Multi=4}
1D: CCSD(T)/cc-pVTZ
2D: MP2/cc-pVTZ
3D: MP2/cc-pVDZ
{SURF,Start1D=label1
VMULT,Start2D=label2,Start3D=label3
VMULT,Var2D=EMP2,Multi=4}
START2D=label
VAR2D=variable
In 2D and 4D calculations (i.e. NDIM=2,4) the VMULT command
can be used as well. In 4D calculations the last level must always
be identical to the 3D level. In 2D the meaning of MULTI=1 and
MULTI=3 is the same. Likewise, MULTI=2 and MULTI=4 are the
same in case of 2D calculations.
START2D and START3D define labels in the input stream in order to
compute the 2D and 3D terms at different levels of electronic structure
theory than the 1D terms. The use of the START2D and START3D
commands usually requests the use of GOTO commands in the input.
The keywords VAR2D and VAR3D are defined in full analogy to the
VAR1D option. They specify the internal variable (e.g. ENERGY,
EMP2, CCSD, ...) to be read out for a given grid point.
The following example shows a 1D:CCSD(T)/cc-pVTZ; 2D:MP4(SDQ)/cc-pVTZ and 3D:MP2/ccpVTZ
multi-level calculation. As the MP2 energy is a byproduct of the CCSD(T) and MP4(SDQ)
calculations only the 1D grid points will be computed twice (at the CCSD(T) and MP4(SDQ)
levels). The 1D and 2D energies will be obtained from the internal variable ENERGY while the
3D energies make use of the EMP2 variable.
memory,50,m
geomtyp=xyz
orient,mass
geometry={
6
Ethen
C 0.0000000000 0.0000000000 -0.6685890718
C 0.0000000000 0.0000000000 0.6685890718
H 0.0000000000 -0.9240027061 -1.2338497710
H 0.0000000000 0.9240027061 -1.2338497710