*LINEAR RESPONSE
Linear Response module written by T. Saue and H. J. Aa. Jensen [Saue2003].
General control statements
.PRINT
Print level.
Default:
.PRINT
0
Definition of the linear response function
.A OPERATOR
Specification of the A operator (see One-electron operators for details).
.B OPERATOR
Specification of the B operator (see One-electron operators for details).
.OPERATORS
Specification of both the A and B operators (see One-electron operators for details).
.EPOLE
Specification of electric Cartesian multipole operators of order L . Specify order.
Example: Electric dipole operators
- ::
.EPOLE 1
.MPOLE
Specification of magnetic Cartesian multipole operators of order L . Specify order. Example: Magnetic dipole operators
- ::
.MPOLE 1
.TRIAB
Enforce triangularity of response function.
Only one function is calculated.
Default: Deactivated.
.B FREQ
Specify frequencies of operator B.
Example: 3 different frequencies.
.B FREQ
3
0.001
0.002
0.01
Default: Static case.
.B FREQ
1
0.0
.IMAGIN
Employ imaginary frequencies.
.ALLCMB
Form all possible combinations even if imaginary.
Default: Deactivated.
.UNCOUP
Uncoupled calculation.
Control variational parameters
.OCCUP
For each fermion ircop give an Specification of orbital strings of inactive orbitals to include in the linear response calculation.
.VIRTUA
For each fermion ircop give an Specification of orbital strings of virtual orbitals to include in the linear response calculation.
.SKIPEE
Exclude all rotations between occupied positive-energy and virtual positive-energy orbitals.
.SKIPEP
Exclude all rotations between occupied positive-energy and virtual negative-energy orbitals.
Control reduced equations
.MAXITR
Maximum number of iterations.
Default:
.MAXITR
30
.MAXRED
Maximum dimension of matrix in reduced system.
Default:
.MAXRED
200
.THRESH
Threshold for convergence of reduced system.
Default:
.THRESH
1.0D-5
Control integral contributions
The user is encouraged to experiment with these options since they may have an important effect on run time.
.INTFLG
Specify what two-electron integrals to include (default: .INTFLG under **HAMILTONIAN).
.CNVINT
Set threshold for convergence before adding SL and SS integrals to SCF-iterations.
2 (real) Arguments:
.CNVINT
CNVXQR(1) CNVXQR(2)
Default: Very large numbers.
.ITRINT
Set the number of iterations before adding SL and SS integrals to SCF-iterations.
Default:
.ITRINT
1 1
Control trial vectors
.REAXVC
Read solution vectors from file XVCFIL
.REAXVC
XVCFIL
Default: No restart on solution vectors. The file has to have six characters. Make sure there is no blank character in front of the file name.
For a restart on solution vectors it is useful to set
.REAXVC
XVCFIL
.ITRINT
0 0
otherwise LS-integrals (and SS-integrals) are switched on later and one may first iterate away and then back to a possibly converged response vector.
Often you have a converged SCF wave function along with a response vector. In this case make sure that
**DIRAC
#.WAVE FUNCTION
is commented out. Make then also sure that you use the DFCOEF file which has been obtained in the same calculation as the response vector file. Otherwise you may observe more response solver iterations than necessary.
.XLRNRM
Normalize trial vectors. Using normalized trial vectors will reduce efficiency of screening. CLARIFY!
Default: Use un-normalized vectors.
Analysis
.ANALYZ
The linear response function is obtained by contracting the property gradient \(\boldsymbol{E}_{A}^{[1]}\) associated with property \(A\) with the solution vector \(\boldsymbol{X}_{B}\) associated with property \(B\):
The indices of the two vectors run over orbital rotation indices, that is, one occupied and one virtual index. This analysis shows the most important contributions from orbital pairs to the dot product as well as the most important occupied and virtual orbitals. More information about these orbitals can then be gleaned from Mulliken population analysis.
.ANATHR
This keyword adjusts the number of terms shown in the above analysis. The threshold is in terms of percentage value to the total value of the linear response function.
Default: \(2.0\).
Advanced/debug flags
.E2CHEK
Generate a complete set of trial vector which implicitly allows the explicit construction of the electronic Hessian. Only to be used for small systems !
.ONLYSF
Only call FMOLI in sigmavector routine: only generate one-index transformed Fock matrix [Saue2003].
.ONLYSG
Only call FMOLI in sigmavector routine: 2-electron Fock matrices using one-index transformed densities [Saue2003].
.STERNHEIM
Set diagonal elements of orbital part of Hessian equal to
for rotations between occupied positive-energy and virtual negative-energy orbitals.
Default: Deactivated.
.STERNC
(Sternheim complement) allows to separate basis set incompleteness from the replacement of an inner sum over negative-energy orbitals only by the full sum. In order to benefit from this functionality (only for specialists !), you should run with print level 2 under properties.
Then you can do a sequence of calculations: 1) .SKIPEP 2) .STERNH 3) .STERNC The diamagnetic contribution of 1) is the non-relativistic expectation value, whereas 2) is the Sternheim approximation, that is replacing orbital energy differences with
With no basis set incompleteness the sum of the diamagnetic contribution 2) and the paramagnetic contribution 3) should equal the diamagnetic contribution of 1).
Default: Deactivated.
.COMPRESSION
Reduce number of orbital variation parameters by checking corresponding elements of gradient vector against a threshold. This may reduce memory.
Default: No compression.
.COMPRESSION
0.0
.NOPREC
No preconditioning of initial trial vectors.
Default: Preconditioning of trial vectors.
.RESFAC
New trial vector will be generated only for variational parameter classes whose residual has a norm that is larger than a fraction 1/RESFAC of the maximum norm.
Default:
.RESFAC
1000.0