User Tools

Site Tools


howto:converging_cutoff

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision
Previous revision
converging_cutoff [2014/02/03 11:20] – remove tailing line in code blocks oschuetthowto:converging_cutoff [2020/08/21 10:15] (current) – external edit 127.0.0.1
Line 1: Line 1:
-====== Introduction ======+====== How to Converge the CUTOFF and REL_CUTOFF ======
  
 +===== Introduction =====
 ''QUICKSTEP'', as with nearly all ab initio Density Functional Theory ''QUICKSTEP'', as with nearly all ab initio Density Functional Theory
 simulation packages, requires the use of a real-space (RS) simulation packages, requires the use of a real-space (RS)
Line 24: Line 25:
 calculations were carried out using CP2K version 2.4. calculations were carried out using CP2K version 2.4.
  
-===== ''QUICKSTEP'' Multi-Grid ===== 
  
-Before we go through the input file, it is worth while to explain+==== ''QUICKSTEP'' Multi-Grid ==== 
 +Before we go through the input file, it is worthwhile to explain
 how the multi-grid is constructed in ''QUICKSTEP'', and how the how the multi-grid is constructed in ''QUICKSTEP'', and how the
 Gaussians are mapped onto the different grid levels. Hopefully this Gaussians are mapped onto the different grid levels. Hopefully this
-will offer the reader with a clear picture of how the key control+will offer the reader a clear picture of how the key control
 parameters affect the grids, and thus the overall accuracy of a parameters affect the grids, and thus the overall accuracy of a
 calculation. calculation.
  
 All multi-grid related settings for a calculation is controlled via All multi-grid related settings for a calculation is controlled via
-keywords in [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html|''MULTIGRID'']] subsection of [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT.html|''DFT'']] subsection in +keywords in [[inp>FORCE_EVAL/DFT/MGRID|MULTIGRID]] subsection of [[inp>FORCE_EVAL/DFT|DFT]] subsection in 
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL.html|''FORCE_EVAL'']]. The number of levels for the multi-grid is defined by +[[inp>FORCE_EVAL|FORCE_EVAL]]. The number of levels for the multi-grid is defined by 
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_NGRIDS|''NGRIDS'']], and by default this is set to 4. The keyword [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']]+[[inp>FORCE_EVAL/DFT/MGRID#NGRIDS|NGRIDS]], and by default this is set to 4. The keyword [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]]
 defines the planewave cutoff (default unit is in Ry) for the defines the planewave cutoff (default unit is in Ry) for the
 //finest// level of the multi-grid.  The higher the planewave cutoff, //finest// level of the multi-grid.  The higher the planewave cutoff,
Line 48: Line 49:
 where \(\alpha\) has a default value of 3.0, and since ''CP2K'' where \(\alpha\) has a default value of 3.0, and since ''CP2K''
 versions 2.0, can be configured by the keyword versions 2.0, can be configured by the keyword
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#list_PROGRESSION_FACTOR|''PROGRESSION_FACTOR'']]. Therefore, the higher the value of [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']]+[[inp>FORCE_EVAL/DFT/MGRID#PROGRESSION_FACTOR|PROGRESSION_FACTOR]]. Therefore, the higher the value of [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]]
 the finer grid for all multi-grid levels. the finer grid for all multi-grid levels.
  
 Having constructed the multi-grid, ''QUICKSTEP'' then needs to map Having constructed the multi-grid, ''QUICKSTEP'' then needs to map
-the Gaussians onto the grids. The keyword [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] controls+the Gaussians onto the grids. The keyword [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] controls
 which product Gaussians are mapped onto which level of the which product Gaussians are mapped onto which level of the
 multi-grid.  ''CP2K'' tries to map each Gaussian onto a grid such multi-grid.  ''CP2K'' tries to map each Gaussian onto a grid such
 that the number of grid points covered by the Gaussian---no matter that the number of grid points covered by the Gaussian---no matter
-how wide or narrow---are roughly the same. [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] defines the+how wide or narrow---are roughly the same. [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] defines the
 planewave cutoff of a reference grid covered by a Gaussian with planewave cutoff of a reference grid covered by a Gaussian with
 unit standard deviation (\(e^{\vert\vec{r}\vert^2}\)). A Gaussian unit standard deviation (\(e^{\vert\vec{r}\vert^2}\)). A Gaussian
Line 62: Line 63:
 function will cover number of grid points greater than or equal to function will cover number of grid points greater than or equal to
 the number of grid points \(e^{\lvert\vec{r}\rvert^2}\) will cover on the number of grid points \(e^{\lvert\vec{r}\rvert^2}\) will cover on
-a reference grid defined by [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']].+a reference grid defined by [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]].
  
 Therefore, the two most important keywords effecting the Therefore, the two most important keywords effecting the
-integration grid and the accuracy of a calculation are [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] and +integration grid and the accuracy of a calculation are [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] and 
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTFF'']]. If [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] is too low, then all grids will be coarse+[[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]]. If [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] is too low, then all grids will be coarse
 and the calculation may become inaccurate; and if ''REL_CUTOFF'' is and the calculation may become inaccurate; and if ''REL_CUTOFF'' is
-too low, then even if you have a high [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']], all Gaussians will+too low, then even if you have a high [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]], all Gaussians will
 be mapped onto the coarsest level of the multi-grid, and thus the be mapped onto the coarsest level of the multi-grid, and thus the
 effective integration grid for the calculation may still be too effective integration grid for the calculation may still be too
 coarse. coarse.
-====== Example: Bulk Si with 8 atoms in a cubic cell ====== 
  
 +
 +===== Example: Bulk Si with 8 atoms in a cubic cell =====
 We demonstrate the process using an example based on Bulk Si with 8 We demonstrate the process using an example based on Bulk Si with 8
 atoms in a face centred cubic unit cell. atoms in a face centred cubic unit cell.
  
-===== Template Input File ===== 
  
-To systematically find the best [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] and [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] values+==== Template Input File ==== 
 +To systematically find the best [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] and [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] values
 which are sufficient for a given accuracy (say, \(10^{-6}\) Ry in total which are sufficient for a given accuracy (say, \(10^{-6}\) Ry in total
 energy), we need to perform a series of single point energy energy), we need to perform a series of single point energy
Line 175: Line 177:
 &END GLOBAL &END GLOBAL
 </code> </code>
-The keyword [[http://manual.cp2k.org/trunk/CP2K_INPUT/GLOBAL.html#desc_RUN_TYPE|''RUN_TYPE'']] is set to ''ENERGY'', this tells ''CP2K'' to only+The keyword [[inp>GLOBAL#RUN_TYPE|RUN_TYPE]] is set to ''ENERGY'', this tells ''CP2K'' to only
 calculate the energies of the system, forces will not be calculate the energies of the system, forces will not be
 calculated. Since we are only interested in the convergence of the calculated. Since we are only interested in the convergence of the
 integration grid, just looking at the total energy usually suffices; integration grid, just looking at the total energy usually suffices;
 and since we will be performing a series of computations, the and since we will be performing a series of computations, the
-cheaper each run is the better. We set [[http://manual.cp2k.org/trunk/CP2K_INPUT/GLOBAL.html#desc_PRINT_LEVEL|''PRINT_LEVEL'']] to ''MEDIUM'', so+cheaper each run is the better. We set [[inp>GLOBAL#PRINT_LEVEL|PRINT_LEVEL]] to ''MEDIUM'', so
 that the information about how many Gaussian functions are mapped that the information about how many Gaussian functions are mapped
 onto which grid are printed. We need this information to analyse the onto which grid are printed. We need this information to analyse the
-suitability of the chosen [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] value.+suitability of the chosen [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] value.
  
 The most important part in the template input is: The most important part in the template input is:
Line 195: Line 197:
 The symbols ''LT_cutoff'' and ''LT_rel_cutoff'' are //markers//, which The symbols ''LT_cutoff'' and ''LT_rel_cutoff'' are //markers//, which
 the automated scripts will search for and replace with the relevant the automated scripts will search for and replace with the relevant
-values. The default units for both [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] and [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] are+values. The default units for both [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] and [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] are
 Ry. Ry.
  
Line 206: Line 208:
 self-consistency, grid settings with fine enough meshes should give self-consistency, grid settings with fine enough meshes should give
 consistent energies. consistent energies.
-===== Converging ''CUTOFF'' ===== 
  
-We start by setting [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] to a relatively high number, and + 
-systematically vary [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']]. Setting [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] to 60 Ry is+==== Converging ''CUTOFF'' ==== 
 +We start by setting [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] to a relatively high number, and 
 +systematically vary [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]]. Setting [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] to 60 Ry is
 usually sufficient for most calculations, and in any case this will usually sufficient for most calculations, and in any case this will
-be checked later when we vary [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']].+be checked later when we vary [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]].
  
-==== Generating Inputs ==== 
  
-We want to perform a series of calculations, with [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] ranging+=== Generating Inputs === 
 +We want to perform a series of calculations, with [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] ranging
 from 50 Ry to 500 Ry in steps of 50 Ry. From experience, the from 50 Ry to 500 Ry in steps of 50 Ry. From experience, the
-desired [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] for an accuracy of \(10^{-6}\) Ry for the total+desired [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] for an accuracy of \(10^{-6}\) Ry for the total
 energy should be well within this range. To do this, we first need energy should be well within this range. To do this, we first need
 to make sure the basis and pseudopotential parameter files to make sure the basis and pseudopotential parameter files
Line 263: Line 266:
 each containing ''BASIS_SET'', ''GTH_POTENTIALS'' and an input file each containing ''BASIS_SET'', ''GTH_POTENTIALS'' and an input file
 ''Si_bulk8.inp'', which is exactly the same as ''template.inp'', except ''Si_bulk8.inp'', which is exactly the same as ''template.inp'', except
-that [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] is set to 60, and [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] is set to the respective+that [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] is set to 60, and [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] is set to the respective
 values in the range between 50 Ry and 500 Ry. values in the range between 50 Ry and 500 Ry.
-==== Running Calculations ==== 
  
 +
 +=== Running Calculations ===
 With the input files generated and checked, the next step is to With the input files generated and checked, the next step is to
 run them. A bash script such as ''cutoff_run.sh'' shown below does run them. A bash script such as ''cutoff_run.sh'' shown below does
Line 309: Line 313:
 used for running all of the jobs. In the above example, the jobs used for running all of the jobs. In the above example, the jobs
 are run on a 24 core local workstation, a total of 16 cores are are run on a 24 core local workstation, a total of 16 cores are
-used for performing the [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] convergence test calculations,+used for performing the [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] convergence test calculations,
 and 2 cores are used for each calculation. This means up to 8 jobs and 2 cores are used for each calculation. This means up to 8 jobs
 will run in parallel, until the jobs are exhausted from the list will run in parallel, until the jobs are exhausted from the list
Line 328: Line 332:
 runs the calculations in the background. This calculation only runs the calculations in the background. This calculation only
 took a couple of minutes to complete on our local workstation. took a couple of minutes to complete on our local workstation.
-==== Analysing Results ==== 
  
 +
 +=== Analysing Results ===
 After all of the calculations have finished, all the information After all of the calculations have finished, all the information
 about total energies and distribution of Gaussians on the about total energies and distribution of Gaussians on the
Line 390: Line 395:
 total gridlevel count  :          10496 total gridlevel count  :          10496
 </code> </code>
-which tells us that for [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] of 100 Ry and [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] of 60+which tells us that for [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] of 100 Ry and [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] of 60
 Ry, 2720 product Gaussians has been distributed to grid level 1, Ry, 2720 product Gaussians has been distributed to grid level 1,
 the finest level, 5000 for level 2, 2760 for level 3 and 16 for the finest level, 5000 for level 2, 2760 for level 3 and 16 for
Line 425: Line 430:
              awk '{print $6}')              awk '{print $6}')
     if $grid_header ; then     if $grid_header ; then
-        for ((igrid=1; igrid <= $ngrids; igrid++)) ; do+        for ((igrid=1; igrid <= ngrids; igrid++)) ; do
             printf " | NG on grid %d" $igrid >> $plot_file             printf " | NG on grid %d" $igrid >> $plot_file
         done         done
Line 432: Line 437:
     fi     fi
     printf "%10.2f  %15.10f" $ii $total_energy >> $plot_file     printf "%10.2f  %15.10f" $ii $total_energy >> $plot_file
-    for ((igrid=1; igrid <= $ngrids; igrid++)) ; do+    for ((igrid=1; igrid <= ngrids; igrid++)) ; do
         grid=$(grep -e '^[ \t]*count for grid' $work_dir/$output_file | \         grid=$(grep -e '^[ \t]*count for grid' $work_dir/$output_file | \
                awk -v igrid=$igrid '(NR == igrid){print $5}')                awk -v igrid=$igrid '(NR == igrid){print $5}')
Line 468: Line 473:
 </code> </code>
  
-The data shows that given the [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] value of 60 Ry, setting +The data shows that given the [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] value of 60 Ry, setting 
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] to 250 Ry and above would give an error in total energy +[[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] to 250 Ry and above would give an error in total energy 
-less than \(10^{-8}\) Ha. The reader may also notice that as [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']]+less than \(10^{-8}\) Ha. The reader may also notice that as [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]]
 increases, the number of Gaussians being assigned to the finest increases, the number of Gaussians being assigned to the finest
-grids decreases. Therefore, simply increasing [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] without +grids decreases. Therefore, simply increasing [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] without 
-increasing [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] may eventually lead to a slow convergence+increasing [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] may eventually lead to a slow convergence
 in energy, as more and more Gaussians get pushed to coarser grid in energy, as more and more Gaussians get pushed to coarser grid
-levels, negating the increase in [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']].+levels, negating the increase in [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]].
  
 In this example, the test results point to 250 Ry as a good choice In this example, the test results point to 250 Ry as a good choice
-for [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']], as the total energy is converged, and the+for [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]], as the total energy is converged, and the
 distribution of Gaussian functions on the grids are reasonable: it distribution of Gaussian functions on the grids are reasonable: it
 is the lowest cutoff energy where the finest grid level is used, is the lowest cutoff energy where the finest grid level is used,
-but at the same time with the majority of the Gaussians on the +but at the same time with the majority of the Gaussians on the coarser grids.
-coarser grids. +
-===== Converging ''REL_CUTOFF'' =====+
  
-In the next step, we vary the value of [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] while keeping 
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] fixed at 250 Ry. 
  
-==== Generating Inputs ====+==== Converging ''REL_CUTOFF'' ==== 
 +In the next step, we vary the value of [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] while keeping 
 +[[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] fixed at 250 Ry.
  
-For the energy convergence test with varying [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']], we + 
-follow a similar procedure as that for [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']]. Using the same+=== Generating Inputs === 
 +For the energy convergence test with varying [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]], we 
 +follow a similar procedure as that for [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]]. Using the same
 template input file ''template.inp'', we can write a script called template input file ''template.inp'', we can write a script called
 ''rel_cutoff_inputs.sh'': ''rel_cutoff_inputs.sh'':
Line 526: Line 531:
 each containing files ''BASIS_SET'', ''GTH_POTENTIALS'' and an input each containing files ''BASIS_SET'', ''GTH_POTENTIALS'' and an input
 ''Si_bulk8.inp'', which is identical to ''template.inp'', except that ''Si_bulk8.inp'', which is identical to ''template.inp'', except that
-[[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] is set to 250, and [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] is set to 10, 20, ...,+[[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] is set to 250, and [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] is set to 10, 20, ...,
 100 respectively. 100 respectively.
-==== Running Calculations ==== 
  
 +
 +=== Running Calculations ===
 Again to run the calculations, we can use the script Again to run the calculations, we can use the script
 ''rel_cutoff_run.sh'', as shown below: ''rel_cutoff_run.sh'', as shown below:
Line 568: Line 574:
 ./rel_cutoff_run.sh & ./rel_cutoff_run.sh &
 </code> </code>
-==== Analysing Results ==== 
  
 +
 +=== Analysing Results ===
 Total energies and distribution of Gaussian functions on the Total energies and distribution of Gaussian functions on the
 multi-grid are obtained the same way from the results as that for multi-grid are obtained the same way from the results as that for
-the [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_CUTOFF|''CUTOFF'']] calculations.+the [[inp>FORCE_EVAL/DFT/MGRID#CUTOFF|CUTOFF]] calculations.
  
-To put all of the results from the [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] calculations in+To put all of the results from the [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] calculations in
 one place, we can make some minor modifications to one place, we can make some minor modifications to
 ''cutoff_analyse.sh'' and save it as ''rel_cutoff_analyse.sh'': ''cutoff_analyse.sh'' and save it as ''rel_cutoff_analyse.sh'':
Line 601: Line 608:
              awk '{print $6}')              awk '{print $6}')
     if $grid_header ; then     if $grid_header ; then
-        for ((igrid=1; igrid <= $ngrids; igrid++)) ; do+        for ((igrid=1; igrid <= ngrids; igrid++)) ; do
             printf " | NG on grid %d" $igrid >> $plot_file             printf " | NG on grid %d" $igrid >> $plot_file
         done         done
Line 608: Line 615:
     fi     fi
     printf "%10.2f  %15.10f" $ii $total_energy >> $plot_file     printf "%10.2f  %15.10f" $ii $total_energy >> $plot_file
-    for ((igrid=1; igrid <= $ngrids; igrid++)) ; do+    for ((igrid=1; igrid <= ngrids; igrid++)) ; do
         grid=$(grep -e '^[ \t]*count for grid' $work_dir/$output_file | \         grid=$(grep -e '^[ \t]*count for grid' $work_dir/$output_file | \
                awk -v igrid=$igrid '(NR == igrid){print $5}')                awk -v igrid=$igrid '(NR == igrid){print $5}')
Line 642: Line 649:
 </code> </code>
  
-The results show that as one increases the value of [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']],+The results show that as one increases the value of [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]],
 more Gaussians get mapped onto the finer grids. The error in total more Gaussians get mapped onto the finer grids. The error in total
-energy reduces to less than \(10^{-8}\) Ha when [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']] is+energy reduces to less than \(10^{-8}\) Ha when [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]] is
 greater or equal to 60 Ry. The results thus indicate that 60 Ry is greater or equal to 60 Ry. The results thus indicate that 60 Ry is
-indeed a suitable choice for the value of [[http://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/MGRID.html#desc_REL_CUTOFF|''REL_CUTOFF'']].+indeed a suitable choice for the value of [[inp>FORCE_EVAL/DFT/MGRID#REL_CUTOFF|REL_CUTOFF]].
  
 So finally we conclude that the setting So finally we conclude that the setting
howto/converging_cutoff.1391426459.txt.gz · Last modified: 2020/08/21 10:15 (external edit)