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113 lines
3.0 KiB
Org Mode
113 lines
3.0 KiB
Org Mode
#+TITLE: Hartree-Fock
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#+PROPERTY: header-args :tangle ex_hartree_fock.ml :comments link :exports code
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In this example, we write a program that makes a Hartree-Fock
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calculation. The molecule is read in =xyz= format and a Gaussian
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atomic basis set in GAMESS format.
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* Header
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#+BEGIN_SRC ocaml
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module Command_line = Qcaml.Common.Command_line
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module Util = Qcaml.Common.Util
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let () =
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#+END_SRC
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* Command-line arguments
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We use the =Command_line= module to define the following possible
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arguments:
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- =-b --basis= : The name of the file containing the basis set
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- =-x --xyz= : The name of the file containing the atomic coordinates
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- =-c --charge= : The charge of the molecule
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- =-m --multiplicity= : The spin multiplicity
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** Definition
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#+BEGIN_SRC ocaml
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let open Command_line in
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begin
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set_header_doc (Sys.argv.(0));
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set_description_doc "Computes the one- and two-electron hartree_fock on the Gaussian atomic basis set.";
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set_specs
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[ { short='b' ; long="basis" ; opt=Mandatory;
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arg=With_arg "<string>";
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doc="Name of the file containing the basis set"; } ;
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{ short='x' ; long="xyz" ; opt=Mandatory;
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arg=With_arg "<string>";
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doc="Name of the file containing the nuclear coordinates in xyz format"; } ;
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{ short='m' ; long="multiplicity" ; opt=Optional;
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arg=With_arg "<int>";
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doc="Spin multiplicity (2S+1). Default is singlet"; } ;
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{ short='c' ; long="charge" ; opt=Optional;
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arg=With_arg "<int>";
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doc="Total charge of the molecule. Specify negative charges with 'm' instead of the minus sign, for example m1 instead of -1. Default is 0"; } ;
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]
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end;
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#+END_SRC
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** Interpretation
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#+BEGIN_SRC ocaml
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let basis_file = Util.of_some @@ Command_line.get "basis" in
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let nuclei_file = Util.of_some @@ Command_line.get "xyz" in
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let charge =
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match Command_line.get "charge" with
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| Some x -> ( if x.[0] = 'm' then
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~- (int_of_string (String.sub x 1 (String.length x - 1)))
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else
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int_of_string x )
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| None -> 0
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in
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let multiplicity =
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match Command_line.get "multiplicity" with
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| Some x -> int_of_string x
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| None -> 1
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in
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#+END_SRC
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* Computation
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We first read the =xyz= file to create a molecule:
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#+BEGIN_SRC ocaml
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let nuclei =
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Qcaml.Particles.Nuclei.of_xyz_file nuclei_file
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in
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#+END_SRC
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Then we create a Gaussian AO basis using the atomic coordinates:
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#+BEGIN_SRC ocaml
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let ao_basis =
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Qcaml.Ao.Basis.of_nuclei_and_basis_filename ~nuclei basis_file
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in
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#+END_SRC
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We create a simulation from the nuclei and the basis set:
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#+BEGIN_SRC ocaml
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let simulation = Qcaml.Simulation.make ~multiplicity ~charge ~nuclei ao_basis in
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#+END_SRC
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and we can make the Hartree-Fock computation:
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#+BEGIN_SRC ocaml
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let hf = Qcaml.Mo.Hartree_fock.make ~guess:`Huckel simulation in
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#+END_SRC
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* Output
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We print the convergence of the calculation:
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#+BEGIN_SRC ocaml
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Format.printf "@[%a@]" (Mo.Hartree_fock.pp) hf
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#+END_SRC
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