# psi4/psi4

Switch branches/tags
Nothing to show
Fetching contributors…
Cannot retrieve contributors at this time
57 lines (43 sloc) 1.63 KB
 #! RHF cc-pVDZ energy for water, automatically scanning the symmetric stretch and bending coordinates #! using Python's built-in loop mechanisms. The geometry is specified using a Z-matrix with variables #! that are updated during the potential energy surface scan, and then the same procedure is performed #! using polar coordinates, converted to Cartesian coordinates. # Define the points on the potential energy surface using standard Python list functions Rvals = [ 0.9, 1.0, 1.1 ] Avals = range(102, 106, 2) # Start with a potential energy scan in Z-matrix coordinates molecule h2o { O H 1 R H 1 R 2 A } count = 0 set basis cc-pvdz set scf e_convergence = 11 set scf_type pk for R in Rvals: h2o.R = R for A in Avals: h2o.A = A thisenergy = energy('scf') count = count + 1 # And now the same thing, using Python's trigonometry functions, and Cartesian input. This time # we want to reset the Cartesian positions every time the angles and bond lengths change, so we # define the geometry inside the loops. N.B. this requires the basis set to be re-specified after # every change of geometry count = 0 for R in Rvals: for A in Avals: molecule h2o { O 0.0 0.0 0.0 H 0.0 R 0.0 H 0.0 RCosA RSinA } # The non-numeric entries above just define placeholders with names. They still need # to be set, which we do below. h2o.R = R h2o.RCosA = R * math.cos(math.radians(A)) h2o.RSinA = R * math.sin(math.radians(A)) set basis cc-pvdz thisenergy = energy('scf') count = count + 1