Set default max stepsize for optimization in Gaussian

As suggested by Duminda, setting MaxStep = 5 in Gaussian gives better TS
result. The default value in G16 is MaxStep = 30 (less rigorious)

arc/job/job.py

@@ -427,7 +427,7 @@ def write_input_file(self):
                     # Note that the Acc2E argument is not available in Gaussian03
                     fine = 'scf=(tight, direct) integral=(grid=ultrafine, Acc2E=12)'
                     if self.is_ts:
-                        job_type_1 = 'opt=(ts, calcfc, noeigentest, tight)'
+                        job_type_1 = 'opt=(ts, calcfc, noeigentest, tight, maxstep=5)'
                     else:
                         job_type_1 = 'opt=(calcfc, noeigentest, tight)'
             elif self.software == 'qchem':