Fix #102. Handle zero beta electrons in UCCSD
Fix #102. Handle zero beta electrons in UCCSD

gkc1000/pyscf,gkc1000/pyscf,sunqm/pyscf,gkc1000/pyscf,sunqm/pyscf,sunqm/pyscf,sunqm/pyscf,gkc1000/pyscf,gkc1000/pyscf