echo
start h2o

memory global 40 mb stack 23 mb heap 5 mb

basis
  O library 6-31g*
  H library 6-31g*
end


geometry noautoz noautosym nocenter units au
 O                     0.00000000     0.00000000     0.00000000
 H                     0.23701217     0.50006465    -0.66134565
 H                     0.08518191    -0.91769081    -0.30894068
end

####################################
#      TESTING FIXED ATOMS         #
####################################

#we can fix atoms two ways through geometry:actlist 
#or through constraint module

set geometry:actlist  3
task dft gradient

unset geometry:actlist
constraints 
  fix atom 1:2
end
task dft gradient

#we can also mix both geometry:actlist 
#and constraints
#in this particular case only atom 2 will be fixed

set geometry:actlist  1
constraints 
  fix atom 1:2
end
task dft gradient

#we can also play with namespaces

constraints one
fix atom 1
end

constraints two
fix atom 2
end

set constraints one
task dft gradient

set constraints two
task dft gradient

#we can clear constraints
constraints one
clear
end

set constraints one
task dft gradient

