ORCA Freq Parser (TS)

[calvinp0]

ORCA, when used to parse for neg freq in a TS, would not pick up the negative freq. It would throw it away due to the line of code saying freq > 0.

[Copilot]

Pull request overview

This PR fixes a bug in the ORCA frequency parser where negative frequencies (imaginary modes) in transition states were incorrectly filtered out. The parser now correctly handles both positive and negative frequencies while still excluding exact zeros (translations/rotations).

Key changes:

• Modified the frequency filtering logic from freq > 0 to abs(freq) > 0.0 to preserve negative frequencies
• Added a test case with ORCA transition state output containing a negative frequency
• Included comprehensive test data file with a transition state calculation showing -1271.62 cm⁻¹ imaginary mode

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
arc/parser/adapters/orca.py	Fixed frequency filtering logic to preserve negative frequencies while excluding exact zeros
arc/parser/parser_test.py	Added test case for ORCA transition state with negative frequency
arc/testing/freq/orca_neg_freq_ts.out	New test data file containing ORCA TS calculation with imaginary mode at -1271.62 cm⁻¹

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