If a system has exactly one coordinate to be optimized, then obviously one
line-search will optimize the geometry. Because of this, the geometry
optimization is done a little differently. Given the initial geometry, the
ΔH_{f
} is calculated, and the line-search started. Unlike the normal
line-search, however, the search is not stopped when the minimum is almost
reached, instead, the minimum is located with quite high precision. After the
line-search is complete, the gradients are not calculated
(unless requested by GRADIENTS). Instead, it is assumed that the
gradient is small, and the results are output. This saves some time. However,
if GRADIENTS is not present, and the geometry is not at a
stationary point (because other coordinates are not optimized), then the
warning message that the geometry is not at a stationary point will not be
printed.