# compare_fchkfiles¶

psi4.driver.compare_fchkfiles(expected, computed, atol_exponent, label)[source]

Comparison function for output data in FCHK (formatted checkpoint) file format. Compares many fields including number of electrons, highest angular momentum, basis set exponents, densities, final gradient.

Note only Psi4-style signature ((expected, computed, atol_exponent, label)) available.

An older format description can be found here http://wild.life.nctu.edu.tw/~jsyu/compchem/g09/g09ur/f_formchk.htm It lists more fields (logical, character) that are not included in this test function. They should be covered by the string comparison. This function is only meant to work with PSI4’s FCHK files.

Parameters:
• expected (str) – Path to reference FCHK file against which computed is compared.

• computed (str) – Path to input FCHK file to compare against expected.

• atol_exponent (Union[int, float]) – Absolute tolerance for high accuracy fields – 1.e-8 or 1.e-9 is suitable. Values less than one are taken literally; one or greater taken as decimal digits for comparison. So 1 means atol=0.1 and 2 means atol=0.01 but 0.04 means atol=0.04 Note that the largest expressable processed atol will be ~0.99.

• label (str) – Label for passed and error messages.