Content:

1. Basic input
2. Optional input
3. Advanced input

1. Basic input

Every calculation requires four essential input arguments for the input keywords code, code_exe, method, and xyz.

These inputs are processed by the ‘calculator’ function of the pople code as arbitray keyword arguments (**kwargs) .

These keywords and their arguments are provided to the ‘calculator’ function as

pople.calculator(key1=arg1, key2=arg2, key3=arg3, key4=arg4)

Here is a specific example

from pople import calculator as calc
out = calc(code='orca', code_exe='/home/Lib/ORCA_420/orca', method='g4mp2', xyz=geom)

See also example-1 from Tutorials

Keyword: code

Argument (string): presently, 'orca' is the only allowed argument
Usage:

code='orca'  

Keyword: code_exe

Argument (string): Absolute path of the executable binary of the code
Usage-1:

code_exe='/home/Lib/ORCA_420/orca'   

Usage-2:

exe='/home/Lib/ORCA_420/orca'   
code_exe=exe   

Keyword: method

Argument (string): Pople (version-21.04.0) supports 'g4mp2' and 'g4mp2-xp' calculations
Usage:

method='g4mp2-xp'    

Keyword: xyz

Argument (string): Name of the geometry block. The geometry block collects the charge, multiplicity and Cartesian coodinates (in Angstroem) of the atom/molecule under consideration.
Usage:

geom='''  
0   1   
O      0.0         0.0      0.0   
H      0.96854     0.0      0.0   
H     -0.22812     0.0     -0.94129   
'''   
  
xyz=geom   

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2. Optional input

Keyword: nproc

Argument (integer): Number of cpu-cores for a parallel calculation
Default: 1
Usage:

nproc=4    

Usage of this keyword assumes that the library variables are set properly. For example, these may be set on the terminal (or in a job script) as follows

export OMP_NUM_THREADS=1
export PATH=/apps/openmpi-3.0.0_install/bin:$PATH
export LD_LIBRARY_PATH=/apps/openmpi-3.0.0_install/lib:$LD_LIBRARY_PATH

Keyword: mem_mb

Argument (integer): RAM memory per core in megabytes
Default: 1000
Usage:

mem_mb=4000   

Keyword: frozengeom

Argument (string): 'true' for a frozen-geometry calculation.
Usage:

frozengeom='true'    

If set to 'true', the keyword 'freqcmi' [next keyword below] has to be provided to ‘calculator’ See the test job test_003_enthalpy_H2_frozen_geom

Keyword: freqcmi

Argument (string): Name of the frequency block containing harmonic wavenumbers in cm^-1 Usage:

freq='''     
1671.78  
3808.42   
3912.50   
'''   
  
freqcmi=freq   

See the test job test_003_enthalpy_H2_frozen_geom

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3. Advanced input

Coming soon

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