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exercises:2017_uzh_cp2k-tutorial:hybrid

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exercises:2017_uzh_cp2k-tutorial:hybrid [2017/07/11 23:48] – gtocciexercises:2017_uzh_cp2k-tutorial:hybrid [2020/08/21 10:15] (current) – external edit 127.0.0.1
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 <note> <note>
-Tutorial re-adapted from [[https://www.cp2k.org/exercises:2016_summer_school:hfx]] +Tutorial re-adapted from the [[https://www.cp2k.org/exercises:2016_summer_school:hfx| Tutorial on HFX and ADMM 2016 at KCL]] 
-For more info see also the slides from Joost VandeVondele [[https://www.cecam.org/upload/talk/presentation_5766.pdf]] +For more info see also the slides from Joost VandeVondele [[pdf>https://www.cecam.org/upload/talk/presentation_5766.pdf| presentation 2011]], Sanliang Ling [[pdf>https://www.cp2k.org/_media/events:2016_user_meeting:cp2k-uk-2016-ling.pdf | presentation 2016]] and 
-and Sanliang Ling [[https://www.cp2k.org/_media/events:2016_user_meeting:cp2k-uk-2016-ling.pdf]]+Matt Watkins [[https://mattatlincoln.github.io/cp2k_workshop_2017 | presentation 2017]]
 </note> </note>
  
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    ! various runtypes (energy, geo_opt, etc.) available.    ! various runtypes (energy, geo_opt, etc.) available.
    RUN_TYPE ENERGY    RUN_TYPE ENERGY
-   ! limit the runs to 5min +   ! amount of information printed to output
-   WALLTIME 1800 +
-   ! reduce the amount of IO+
    IOLEVEL  MEDIUM    IOLEVEL  MEDIUM
 &END GLOBAL &END GLOBAL
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          SCF_GUESS ATOMIC ! can be used to RESTART an interrupted calculation          SCF_GUESS ATOMIC ! can be used to RESTART an interrupted calculation
          MAX_SCF 30          MAX_SCF 30
-         EPS_SCF 1.0E-6 ! accuracy of the SCF procedure typically 1.0E-6 - 1.0E-7+         EPS_SCF 1.0E-6 ! accuracy of the SCF procedure, for OT typically 1.0E-6 - 1.0E-7, for diagonalization may have to be smaller
          &OT          &OT
             ! an accurate preconditioner suitable also for larger systems             ! an accurate preconditioner suitable also for larger systems
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           ! important parameter to get stable HFX calcs (contributions to hfx smaller than EPS_SCHWARZ are not considered)           ! important parameter to get stable HFX calcs (contributions to hfx smaller than EPS_SCHWARZ are not considered)
           EPS_SCHWARZ 1.0E-6           EPS_SCHWARZ 1.0E-6
-          ! needs a good (GGA) initial guess (screening on density matrix elements)+          ! needs a good (GGA) initial guess  
 +          ! screening on the product between maximum of density matrix elements and ERI
           SCREEN_ON_INITIAL_P TRUE           SCREEN_ON_INITIAL_P TRUE
         &END         &END
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   * Look at the output where the HOMO-LUMO gap has been printed out. How does this compare to the GGA result?    * Look at the output where the HOMO-LUMO gap has been printed out. How does this compare to the GGA result? 
   * Adjust the fraction of exchange (modify the input in two places!) to 20% and/or 30%, how does this influence the gap ?   * Adjust the fraction of exchange (modify the input in two places!) to 20% and/or 30%, how does this influence the gap ?
-  * Most of the time in the SCF cycle is spent in the first step, while the other steps are much faster. Why do you think is that?+  * The most expensive part of the whole SCF cycle is represented by the first step, while the other steps are much faster. Why is that?
   * __Optional__ You can check if the SCF cycle is stable by decreasing the values of ''EPS_PGF_ORB'', ''EPS_FILTER_MATRIX'' as well as ''EPS_SCHWARZ''. Re-run the calculation and see how this affects the ''ENERGY''.   * __Optional__ You can check if the SCF cycle is stable by decreasing the values of ''EPS_PGF_ORB'', ''EPS_FILTER_MATRIX'' as well as ''EPS_SCHWARZ''. Re-run the calculation and see how this affects the ''ENERGY''.
   * __Optional__ CP2K tries to store the ERI in-core and avoid to calculate them at each SCF step. Especially for large systems that can be run on large HCP machines it is important to run in-core operation and fit the calculations of the ERI into memory. To see the effect of not having enough memory on the time for the ''SCF'' cycle, modify the tag of ''MAX_MEMORY'' to 40 and rerun the calculation. How do the timings compare with those where ''MAX_MEMORY'' was larger?   * __Optional__ CP2K tries to store the ERI in-core and avoid to calculate them at each SCF step. Especially for large systems that can be run on large HCP machines it is important to run in-core operation and fit the calculations of the ERI into memory. To see the effect of not having enough memory on the time for the ''SCF'' cycle, modify the tag of ''MAX_MEMORY'' to 40 and rerun the calculation. How do the timings compare with those where ''MAX_MEMORY'' was larger?
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   RUN_TYPE ENERGY   RUN_TYPE ENERGY
   ! limit the runs to 30min   ! limit the runs to 30min
-  WALLTIME 1800+  WALLTIME 1800 
   ! reduce the amount of IO   ! reduce the amount of IO
   IOLEVEL  MEDIUM    IOLEVEL  MEDIUM 
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     ! Charge and multiplicity     ! Charge and multiplicity
-    CHARGE 0 +    CHARGE 1 
-    MULTIPLICITY 1+    MULTIPLICITY 2
  
     &MGRID     &MGRID
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