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Notes on Options


The options referred to in the Theoretical Methods: SCF to FCI section below and indexed in Keywords by Module are placed in set blocks as described in Job Control, not as arguments to a Python function (like energy()).


All PSI4 keyword names and values are insensitive to case, both those that are placed in set blocks and as Python function arguments. The few exceptions are documented for the database() function, where case structure must match the database file.


Boolean options can be specified by yes, on, true, or 1 for affirmative and no, off, false, or 0 for negative, all insensitive to case.


Certain convergence and tolerance keywords, of type double (real numbers), may be specified using either a real number of an integer; and integer X is then treated as the number of converged decimal digits required. For example, to request as energy converged to 10^{-6} E_h, the user may set the e_convergence keyword to 0.000001, 1.0e-6, or 6.

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