Yes. The 'pulse_gen' primitive generates a single-occurring pulse when either the 'width' or 'period' parameter is set to a negative value (e.g. -1). For instance, a 'pulse_gen' primitive with its 'init_value' parameter set to 0, 'delay' parameter set to 3.0us, and 'width' parameter set to -1 produces a single step waveform that starts at 0 and transitions to 1 at 3.0us.

On the other hand, when the 'pulse_gen' primitive has its 'width' parameter set to 2.0us and 'period' parameter set to -1, it produces a single pulse waveform that starts at 0, transitions to 1 at 3.0us, and transitions back to 0 at 5.0us as shown below.