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quickstart [2025/10/14 08:00] – [Simple input] wernerquickstart [2025/10/14 08:54] (current) – [Simple input] werner
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 This computes the ground state and 4 excited states for each of the four IRREPS of C2v. This computes the ground state and 4 excited states for each of the four IRREPS of C2v.
  
-8.) MRCI calculation using state-averaged CASSCF reference:+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}'' ''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.+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.