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quickstart [2025/10/13 13:33] – [Simple input] wernerquickstart [2025/10/14 08:54] (current) – [Simple input] werner
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 ''run DF-KS,b3lyp geometry=h2o.xyz basis=avtz'' ''run DF-KS,b3lyp geometry=h2o.xyz basis=avtz''
  
-where avtz is a short name for the aug-cc-pVTZ basis. The prefix DF- turns on density fitting approximations for the integrals, which is strongly recommended for efficiency, in particular for larger molecules.+where avtz is a short name for the aug-cc-pVTZ basis, and 
 +the geometry is provided in an external file holding the x,y,z coordinates in Angstrom. Alternatively, the geometry can be given as z-matrix in curley brackets.  
 + 
 +The prefix DF- turns on density fitting approximations for the integrals, which is strongly recommended for efficiency, in particular for larger molecules.
  
 A most simple example for a CCSD(T) input is: A most simple example for a CCSD(T) input is:
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 ''run CCSD(T) geometry=h2o.xyz basis=avtz'' ''run CCSD(T) geometry=h2o.xyz basis=avtz''
  
-where the geometry is provided in an external file holding the x,y,z coordinates in Angstrom. Alternatively, the geometry can be given as z-matrix in curley brackets.  
  
 The entries can come in any order, for example The entries can come in any order, for example
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 All higher order methods contain the lower-level ones. For example, ccsd(t) contains HF, MP2, and CCSD, and MRCI contains CASPT2.  All higher order methods contain the lower-level ones. For example, ccsd(t) contains HF, MP2, and CCSD, and MRCI contains CASPT2. 
  
-For larger molecules, it is advisable to use density fitted methods. The following ones are efficiently implemented: +''For larger molecules, it is advisable to use density fitted methods (activated by the prefix DF-).'' Note that in some other programs this is denoted RI-approximation, but in Molpro RI refers to resolution of the identity approximations of the many-electron integrals in F12 methods. This is distinct from DF-approximations of standard 2-electron Coulomb integrals.  
 + 
 +The following ones are efficiently implemented: 
  
  <code>  <code>
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 PNO methods are density fitted in any case.  PNO methods are density fitted in any case. 
  
-For most listed correlation methods, explicitly correlated versions are available by appending -f12 to the command [e.g. ccsd(t)-f12, or pro-lccsd(t)-f12]. The use of F12 methods is strongly recommended since the basis set error is much reduced. Appropriate basis sets for such calculations are avtz or avtz-f12. F12 is not available for MRCIC and NEVPT2.+For most listed correlation methods, explicitly correlated versions are available by appending -F12 to the command [e.g. ccsd(t)-f12, or pno-lccsd(t)-f12]. ''The use of F12 methods is strongly recommended since the basis set error is much reduced.'' Appropriate basis sets for such calculations are avtz or avtz-f12. F12 is not available for MRCIC and NEVPT2.
  
 Method, geometry, and basis set are compulsory for running a calculation. By default, only a single energy calculation is done. However, other calculation types can be requested by specifying one of the following directives (the parts in brackets can be omitted or are optional): Method, geometry, and basis set are compulsory for running a calculation. By default, only a single energy calculation is done. However, other calculation types can be requested by specifying one of the following directives (the parts in brackets can be omitted or are optional):
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 ''run caspt2 geometry=h2o.xyz basis=avtz'' ''run caspt2 geometry=h2o.xyz basis=avtz''
  
 +6.) TDDFT excitation energies:
 +
 +''run df-tddft,states=[4.1,4.2,4.3,4.4] functional=b3lyp basis=avtz geometry=h2o.xyz''
 +
 +This computes 4 excited states for each of the four IRREPS of C2v.
 +
 +7.) CC2 excitation energies:
 +
 +''run df-cc2,states=[4.1,4.2,4.3,4.4] basis=avtz geometry=h2o.xyz''
 +
 +This computes the ground state and 4 excited states for each of the four IRREPS of C2v.
 +
 +8.)CASSCF calculation using state-averaging over three state symmetries:
 +
 +''run casscf wfsym=[2,3,1] spin=1 geometry={O;H,O,1.83}''
 +
 +This carries out a state-averaged CASSCF calculation for symmetries 2,3,1 ($^2\Pi_x$,$^2\Pi_y$, and $^2\Sigma^+$).
 +
 +9. )MRCI calculation using state-averaged CASSCF reference functions:
 +
 +''run mrci wfsym=[2,3,1] spin=1 geometry={O;H,O,1.83}''
 +
 +In this case first a state-averaged CASSCF calculation for symmetries 2,3,1 ($^2\Pi_x$,$^2\Pi_y$,  and $^2\Sigma^+$) is carried out. Subsequently an MRCI calculation is done for each state symmetry separately.
 +
 +
 +10.) Several run command lines can follow each other. For example, compute the lowest ionisation potential of H2O using MRCI:
 +
 +<code>
 +run mrci basis=vtz geometry=h2o.xyz  !casscf/mrci for neutral ground state
 +eci=energy                           !save mrci energy in variable eci
 +eda=energd                           !save mrci+q (Davidson corrected) energy in variable eda
 +run mrci charge=1 wfsym=3 spin=1     !calculation for 2B2 state
 +ipci=(energy-eci)*toev               !compute mrci ionization potential in ev  
 +ipda=(energd-eda)*toev               !compute mrci+q ionization potential in ev
 +</code>
 +
 +11.) It is also possible to combine the run command with other standard molpro input, for example:
 +
 +<code>
 +geometry={O;                 !Z-matrix for water
 +          H1,O,R;
 +          H2,O,R,H1,THETA}
 +basis=vtz                    !use VTZ basis
 +R=0.96 Ang                   !start bond distance
 +Theta=104                    !start bond angle
 +
 +run mp2 optg                 !optimize MP2 energy
 +mp4                          !do single-point MP4 at MP2 geometry
 +ccsd(t)                      !do single-point CCSD(T) at MP2 geometry
 +</code>
 The following sections give more basic information about carrying electronic structure calculations with Molpro. The following sections give more basic information about carrying electronic structure calculations with Molpro.