Gaussian 16 Revision C.01 < TRUSTED | 2024 >

Revision C.01 introduced a change that wasn’t in the notes. In the middle of a long optimization, after dozens of small, precise steps, the calculation converged on a geometry that made her breath catch. It was unexpected not because it was low in energy—though it was—but because it embodied a symmetry she had not anticipated. The electrons arranged themselves in a way that bent her assumptions: a bridge of charge across what had looked previously like an insurmountable barrier, a fleeting structure stabilized by correlation effects the older versions had blurred into noise.

Additionally, the NEDA=n keyword was introduced to perform Natural Energy Decomposition Analysis, a method for quantifying intermolecular interactions. The analysis uses the same fragment definitions as counterpoise calculations for basis set superposition error (BSSE) correction, providing a unified workflow. gaussian 16 revision c.01