QCVariables: setting and accessing

API and conventions to access and program with QCVariables.

Operation	Py-side Globals [1] [5]	Py-side Wavefunction [1] [5]	C-side Globals [3] [4]	C-side Wavefunction [5]
access var	variable()	variable()	val = P::e.globals["KEY"]; val = P::e.arrays["KEY"];	Wavefunction::scalar_variable("kEy") Wavefunction::array_variable("kEy")
access all vars	variables()	variables()	P::e.globals; P::e.arrays;	Wavefunction::scalar_variables() Wavefunction::array_variables()
is var set?	has_variable()	has_variable()	P::e.globals.count("KEY"); P::e.arrays.count("KEY");	Wavefunction::has_scalar_variable("kEy") Wavefunction::has_array_variable("kEy")
set a var value [2]	set_variable()	set_variable()	P::e.globals["KEY"] = val; P::e.arrays["KEY"] = val;	Wavefunction::set_scalar_variable("kEy") Wavefunction::set_array_variable("kEy")
unset var	del_variable()	del_variable()	P::e.globals.erase("KEY") P::e.arrays.erase("KEY")	Wavefunction::del_scalar_variable("kEy") Wavefunction::del_array_variable("kEy")
unset all vars	clean_variables()
register var with docs [6]	core.set_variable("GIBBS", G) # P::e THERMO or # wfn.set_variable("ROOT n") # P::e ADC		P::e.globals["CC T1 DIAG"] = val; or // P::e.globals["CCSD ROOT n"];

[1] (1,2)

Works on float or array variables

[2]

Py-side, value can be float or psi4.core.Matrix or np.ndarray. C-side, value can be float or Matrix, and the appropriate function must be used.

[3]

P::e stands for Process.environment, which is where all the “globals” live in PSI4 .

[4]

P::e access is direct, not through functions, so all variable names must be ALL CAPS.

[5] (1,2,3)

Note that QCVariables are stored all uppercase. Getter/setter functions will do the conversion, so you can use arbitrary case (indicated by "kEy".

[6]

In-code way works for explicit keys; in-comment way needed with programmatic keys or those with variables (the lowercase “n” here). Py-side needs the module specified explicitly, while c-side gets extracted from the src directory.