Ubuntu Manpage: sc::MBPT2_R12 - The MBPT2_R12 class implements several linear R12 second-order perturbation theory

NAME

       sc::MBPT2_R12 - The MBPT2_R12 class implements several linear R12 second-order perturbation theory
       methods.

SYNOPSIS

       #include <mbptr12.h>

       Inherits sc::MBPT2.

   Public Member Functions
       MBPT2_R12 (StateIn &)
       MBPT2_R12 (const Ref< KeyVal > &)
           The KeyVal constructor.
       void save_data_state (StateOut &)
           Save the base classes (with save_data_state) and the members in the same order that the StateIn CTOR
           initializes them.
       Ref< GaussianBasisSet > aux_basis () const
       Ref< GaussianBasisSet > vir_basis () const
       bool gbc () const
       bool ebc () const
       LinearR12::ABSMethod abs_method () const
       LinearR12::StandardApproximation stdapprox () const
       bool spinadapted () const
       R12IntEvalInfo::StoreMethod r12ints_method () const
       const std::string & r12ints_file () const
       double corr_energy ()
       double r12_corr_energy ()
       RefSymmSCMatrix density ()
           Returns the SO density.
       void obsolete ()
           Marks all results as being out of date.
       int gradient_implemented () const
       int value_implemented () const
           Information about the availability of values, gradients, and hessians.
       void print (std::ostream &o=ExEnv::out0()) const
           Print information about the object.

   Protected Member Functions
       void compute ()
           Recompute at least the results that have compute true and are not already computed.

   Additional Inherited Members

Detailed Description

       The MBPT2_R12 class implements several linear R12 second-order perturbation theory methods.

Constructor & Destructor Documentation

sc::MBPT2_R12::MBPT2_R12 (const Ref< KeyVal > &)
The KeyVal constructor.

gbc
This boolean specifies whether Generalized Brillouin Condition (GBC) is assumed to hold. The default
is 'true'. This keyword is only valid if stdapprox=A'. The effect of setting this keyword to true is
rather small -- hence it is not recommended to use this keyword.

ebc
This boolean specifies whether Extended Brillouin Condition (EBC) is assumed to hold. The default is
'true'. This keyword is only valid if stdapprox=A'. The effect of setting this keyword to true is
rather small -- hence it is not recommended to use this keyword.

stdapprox
This gives a string that must take on one of the values below. The default is A'.

A Use second order M/ller-Plesset perturbation theory with linear R12 terms in standard approximation A
(MP2-R12/A). Only energies can be computed with the MP2-R12/A method.

A' Use second order M/ller-Plesset perturbation theory with linear R12 terms in standard approximation
A' (MP2-R12/A'). This will cause MP2-R12/A energies to be computed also. Only energies can be
computed with the MP2-R12/A' method.

B Use second order M/ller-Plesset perturbation theory with linear R12 terms in standard approximation
B. This method is not implemented yet.

spinadapted
This boolean specifies whether to compute spin-adapted or spin-orbital pair energies. Default is to
compute spin-adapted energies.

aux_basis
This specifies the auxiliary basis to be used for the resolution of the identity. Default is to use
the same basis as for the orbital expansion.

vir_basis
This specifies the basis to be used for the virtual orbitals. Default is to use the same basis as for
the orbital expansion.

include_mp1
This specifies whether to compute MP1 correction to the MP2 and MP2-R12 energies. This option only
has effect if vir_basis is not the same as basis. MP1 correction is a perturbative estimate of the
difference between the HF energy computed in vir_basis and basis. Usually, it is a very poor estimate
-- therefore this keyword should be avoided by non-experts. Default is false.

abs_method
This string specifies whether the old ABS method, introduced by Klopper and Samson, or the new ABS
variant, CABS, introduced by Valeev, should be used. Valid values are 'ABS' (Klopper and Samson),
'ABS+', 'CABS', and 'CABS+', where the '+' labels a method where the union of OBS and ABS is used to
construct the RI basis. The default is 'ABS'. The default in 2.3.0 and later will be 'CABS+'.

lindep_tol
The tolerance used to detect linearly dependent basis functions in the RI basis set. The precise
meaning depends on the orthogonalization method. The default value is 1e-8.

r12ints
This specifies how to store transformed MO integrals. Valid values are:

mem-posix
Store integrals in memory for single-pass situations and in a binary file on task 0's node using
POSIX I/O for multipass situations. posix is usually less efficient than mpi for distributed parallel
multipass runs since the I/O is performed by one task only. However, this method is guaranteed to
work in all types of environments, hence mem-posix is the default.

posix
Store integrals in a binary file on task 0's node using POSIX I/O. This method is different from mem-
posix in that it forces the integrals out to disk even if they could be stored in memory. posix
should only be used for benchmarking and testing purposes.

mem-mpi
Store integrals in memory for single-pass situations and in a binary file using MPI-I/O for multipass
situations. This method assumes the availability of MPI-I/O. mem-mpi is the preferred choice in
distributed environments which have MPI-I/O available.

mpi
Store integrals in a binary file using MPI-I/O. This method is different from mem-mpi in that it
forces the integrals out to disk even if they could be stored in memory. mpi should only be used for
benchmarking and testing purposes.

mem
Store integrals in memory. Can only be used with single-pass transformations for MP2-R12/A and
MP2-R12/A' methods. This method should only be used for testing purposes.

If r12ints is not specified, then mem-posix method will be used. If user wishes to use MPI-I/O, pending
its availability, for higher parallel efficiency, r12ints should be explicitly set to mem-mpi.

r12ints_file
This specifies the prefix for the transformed MO integrals file if r12ints is set to posix, mpi, mem-
posix or mem-mpi is used. Default is './<i>inputbasename</i>.r12ints', where inputbasename is the
name of the input file without '.in'. If MPI-I/O is used then it is user's responsibility to ensure
that the file resides on a file system that supports MPI-I/O.

twopdm_grid_aa
This optional keyword specifies a TwoBodyGrid object which to use for coordinates at which to compute
alpha-alpha part of 2-PDM.

twopdm_grid_ab
This optional keyword specifies a TwoBodyGrid object which to use for coordinates at which to compute
alpha-beta part of 2-PDM.

Member Function Documentation

   void sc::MBPT2_R12::compute () [protected],  [virtual]
       Recompute at least the results that have compute true and are not already computed. This should  only  be
       called by Result's members.

       Reimplemented from sc::MBPT2.

   void sc::MBPT2_R12::obsolete () [virtual]
       Marks all results as being out of date. Any subsequent access to results will cause Compute::compute() to
       be called.

       Reimplemented from sc::MBPT2.

   void sc::MBPT2_R12::save_data_state (StateOut &) [virtual]
       Save  the  base  classes  (with  save_data_state) and the members in the same order that the StateIn CTOR
       initializes them. This must be implemented by the derived class if the class has data.

       Reimplemented from sc::MBPT2.

Author

       Generated automatically by Doxygen for MPQC from the source code.

Version 2.3.1                                    Sun Oct 4 2020                                 sc::MBPT2_R12(3)