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general_hints_-_frequently_asked_questions [2024/01/08 13:24] – external edit 127.0.0.1general_hints_-_frequently_asked_questions [2025/02/12 12:12] (current) – molpro: command not found FAQ doll
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   * The active space (occ, frozen, closed) has to be chosen carefully. (Nearly) degenerate states and low lying excited states should be included, based on e.g. SCF eigenvalues.    * The active space (occ, frozen, closed) has to be chosen carefully. (Nearly) degenerate states and low lying excited states should be included, based on e.g. SCF eigenvalues. 
-  * AVAS may help to construct suitable starting orbitals.  +  * AVAS may help to construct suitable starting orbitals. 
 +  * NOEXTRA may be necessary in some cases, e.g. if a previous HF calculation was done with nosym 
  
 ==== MRCI and CASPT2 calculations ==== ==== MRCI and CASPT2 calculations ====
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   * When excited states are computed, then the preceding MCSCF should be state averaged, and include the excited states so that the orbitals from which the MRCI starts are reasonable. E.g.  '' multi;occ,14,4,9,2;frozen,12,1,6,0;wf,47,1,1;state,3'' may be followed by  ''mrci;occ,14,4,9,2;core,12,1,6,0;wf,47,1,1;state,3;''        * When excited states are computed, then the preceding MCSCF should be state averaged, and include the excited states so that the orbitals from which the MRCI starts are reasonable. E.g.  '' multi;occ,14,4,9,2;frozen,12,1,6,0;wf,47,1,1;state,3'' may be followed by  ''mrci;occ,14,4,9,2;core,12,1,6,0;wf,47,1,1;state,3;''     
   * MCSCF and MRCI are not black-box like, and e.g. a visualisation of the MCSCF orbitals will help to set up the active space.   * MCSCF and MRCI are not black-box like, and e.g. a visualisation of the MCSCF orbitals will help to set up the active space.
 +
 +==== molpro: No such file or directory ====
 +
 +After installation, you will usually not be able to call molpro by just typing ''molpro'', and you will get
 +error messages such as e.g. ''No such file or directory'' or ''command not found''.
 +You have to bring ''molpro'' into the path. There are various ways such as setting a symbolic link e.g.
 +from ''$HOME/bin/molpro'' to the installed ''molpro'' or explicity including it in the path.
 +Please use a search engine or a book for such questions about Linux.
 + 
 +==== Hardware ====
 +
 +It is recommended to use a computer with large memory (RAM) and large disk; also a large memory bandwidth is advantageous.
 +We can however not recommend a certain vendor or CPU. For CPU benchmarks, 
 +[[https://www.spec.org|https://www.spec.org]]  may be useful.