Dimer ASD

Description

The active space decomposition algorithm for molecular dimers allows for efficient computation of the dimer’s complete-active-space wave functions. The current algorithm works for dimer molecules whose fragments are not covalently linked. Full-CI and restricted-active-space-CI can be used to obtain the fragment state wave functions. ASD calculation starts with dimer molecule construction, see Dimer Construction section for more information.

Dimer Construction

Keywords

Required Keywords

method

Description: Method to compute active subspaces.
Datatype: string
Value:
cas or fci: use full configuration interaction method
ras: use restricted active space configuration interaction method

fci

Description: If fci is used, specify the implementations here.
Recommendation: See Full configuration interaction (FCI) for details.

ras

Description: If ras is used, specify the implementations here.

space

Description: Specify important fragment states with the following keys:
charge, spin, nstate
Recommendation: See sample input for details.

Optional Keywords

nstates

Description: Number of target states.
Datatype: int
Default 10

charge

Description: Dimer charge.
Datatype: int
Default: 0

nspin

Description: Number of dimer total spin.
Datatype: int
Default: 0

nguess

Description: Number of initial guess state vectors for Davidson diagonalization.
Datatype: int
Default: \(10\times nstates\)

Davidson_subspace

Description: Size of Davidson subspace.
Datatype: int
Default: 10

max_iter

Description: Maximum number of iterations for Davidson diagonalization.
Datatype: int
Default: 50

dipoles

Description: Whether to calculate dipole moment.
Datatype: bool
Default: false

thresh

Description: Threshold for convergence in Davidson diagonalization.
Datatype: double
Default: \(1.0\times 10^{-7}\)

print_thresh

Description: Threshold for printing out important configurations.
Datatype: double
Default: 0.01

store matrix

Description: Whether the Hamiltonian matrix is stored.
Datatye: bool
Default: false

print_info

Description: Whether print out information (e.g. reduced density matrix and energy).
Datatype: bool
Default: false

Example

Here is a sample calculation of a benzene dimer molecule.

alternate text

Sample input

{ "bagel" : [

{
  "title" : "molecule",
  "basis" : "svp",
  "df_basis" : "svp-jkfit",
  "angstrom" : false,
  "cartesian" : false,
  "geometry" : [
    {"atom" :"C", "xyz" : [    0.00000000000,     0.00000000000,     2.64112304663] },
    {"atom" :"C", "xyz" : [    2.28770766388,     0.00000000000,     1.32067631141] },
    {"atom" :"C", "xyz" : [    2.28770047235,     0.00000000000,    -1.32071294538] },
    {"atom" :"C", "xyz" : [    0.00000000000,     0.00000000000,    -2.64114665444] },
    {"atom" :"C", "xyz" : [   -2.28770047235,     0.00000000000,    -1.32071294538] },
    {"atom" :"C", "xyz" : [   -2.28770766388,     0.00000000000,     1.32067631141] },
    {"atom" :"H", "xyz" : [    4.07221260176,     0.00000000000,     2.35164689765] },
    {"atom" :"H", "xyz" : [    4.07221517814,     0.00000000000,    -2.35163163881] },
    {"atom" :"H", "xyz" : [    0.00000000000,     0.00000000000,    -4.70191324441] },
    {"atom" :"H", "xyz" : [   -4.07221517814,     0.00000000000,    -2.35163163881] },
    {"atom" :"H", "xyz" : [   -4.07221260176,     0.00000000000,     2.35164689765] },
    {"atom" :"H", "xyz" : [    0.00000000000,     0.00000000000,     4.70197960246] }
  ]
},

{
  "title" : "hf"
},

{
  "title" : "dimerize",
  "angstrom" : true,
  "translate" : [0.0, 4.0, 0.0],
  "dimer_active" : [17, 20, 21, 22, 23, 24],
  "hf" : {
    "thresh" : 1.0e-12
  },
  "localization" : {
    "max_iter" : 50,
    "thresh" : 1.0e-8
  }
},

{
  "title" : "asd",
  "method" : "cas",
  "store_matrix" : false,
  "space" : [
    { "charge" : 0, "spin" : 0, "nstate" : 3},
    { "charge" : 0, "spin" : 2, "nstate" : 3},
    { "charge" : 1, "spin" : 1, "nstate" : 3},
    { "charge" :-1, "spin" : 1, "nstate" : 3}
  ],
  "fci" : {
    "thresh" : 1.0e-6,
    "algorithm" : "kh",
    "nguess" : 400
  },
  "nstates" : 5
}

]}

Reference

Description of Reference Reference
Active Space Decompotion Method S. M. Parker, T. Seideman, M. A. Ratner, and T. Shiozaki, J. Chem. Phys. 139, 021108 (2013).