NMRCOUPLING subkeys
The available switches within a NMRCOUPLING/END block control the computation of the NSSCCs. By default, the program will evaluate the FC coupling contribution for the first nucleus being the perturbing nucleus and all remaining nuclei responding.
Please note that the ordering of atoms in CPL is generally different from the ADF input. The ordering of atoms is the one being stored in TAPE21 and it is grouped by fragment types. In case you are in doubt about the ordering of atoms, you can run CPL for a few seconds. It will print a list of atoms with their coordinates. The ordering is currently the same as required the NMR program in the ADF program system. On the other hand, note that for the subkeys ATOMPERT and ATOMRESP the number of the atoms refer to the input ordering in the ADF calculation.
Available subkeys are:
NMRCOUPLING NUCLEI {npert nresp1 nresp2} ATOMPERT {npert1 npert2 npert3} ATOMRESP {nresp1 nresp2 nresp3} GAMMA {nnuc gamma} DSO PSO SD FC SCF {ITERATIONS=25 | NOCYCLE | CONVERGE=1e-4 } XALPHA CONTRIBUTIONS {1E19} {LMO, SFO, LMO2, SFO2} END
NUCLEI {npert nresp1 nresp2}
Use nucleus no. npert as the perturbing nucleus, and nuclei nresp1,
nresp2, etc as responding nuclei. You can supply more than one NUCLEI
keys, in which case CPL evaluates the first-order MOs for each perturbing
nucleus that is specified and computes the NSSCCs between all specified
responding nuclei. For each NUCLEI line in the input, CPL has to perform an SCF
cycle. Note: for the numbers of the atoms the internal CPL numbering should
be used.
ATOMPERT {npert1 npert2 npert3}
ATOMRESP {nresp1 nresp2 nresp3}
ATOMPERT: use nucleus no. npert1, npert2, etc. as the perturbing nuclei.
ATOMRESP: use nucleus no. nresp1, nresp2, etc. as the perturbing nuclei.
You can supply more than one ATOMPERT and (or) ATOMRESP key.
CPL computes the NSSCCs for all pairs of combinations of perturbing atoms
and responding atoms.
For each perturbing atom CPL has to perform an SCF cycle, which is the expensive part in the calculation.
Note: the numbers refer to the input ordering in the ADF calculation.
Use the subkey NUCLEI to specify the nuclei according to
the internal CPL numbers of the atoms.
GAMMA {nnuc gamma}
Input a non-default magneto-gyric ratio of g = gamma for nucleus
no. nnuc, in units of rad/(T s). Note that one should include
the the typical 107 factor.
CPL normally uses the g value of the most abundant NMR active
isotope for a nucleus of a given charge by default. With the GAMMA keyword you
can override this value or supply a value if CPL does not know about it. A list
of g's that is used in the computation
is printed in the output. You have to provide the GAMMA key for each
nucleus you want to specify.
DSO
Compute the diamagnetic orbital term for each NSSCC that is
requested (not default)
PSO
Compute the paramagnetic orbital term for each NSSCC (not default)
SD
Compute the SD term for each NSSCC. This is only default for
spin-orbit ADF runs. The output will contain the sum of the FC and SD
contributions. Please note that
requesting this option results in a greatly increased computational cost in
scalar or non-relativistic runs. The option NOSD will turn the SD
computation off in spin-orbit runs and has no effect otherwise.
FC
Compute the FC contribution to the NSSCCs. This is the default
option. Please note that it is currently not possible to compute the SD term
without the FC term. Consult the 'practical aspects' section for instructions
how to estimate the FC/SD cross term. The option NOFC will disable both the
FC and SD computation.
SCF options
Settings related to the SCF cycle that is carried
out by CPL. Valid options are (with default values if applicable):
ITERATIONS 25
maximum number of iterations
NOCYCLE
perform no cycle, equivalent to ITERATIONS 0
CONVERGE 1e-4
convergence criterion, an
input of e corresponds approximately to
a convergence of log(-e) digits, i.e.
the results will be converged to about four significant digits by default. The
measurement for the convergence is based on the sum S of the magnitudes of all occupied-virtual matrix elements of the
induced first-order exchange potential. Note that the actual convergence
criterion being used in the computation is e
times S of the first cycle, i.e. the
convergence criterion is set relative to the initial value of S.
XALPHA
Use first-order Xalpha potential instead of VWN potential. This
will usually decrease the accuracy for couplings involving hydrogen, and does
not have a large effect for couplings between heavier nuclei (not default). The
key is mainly intended to ensure compatibility with our previously published
results.
CONTRIBUTIONS {1e19} {LMO, SFO, LMO2, SFO2}
Print contributions from individual orbitals to the FC and OP term of the
NSSCCs that are larger in magnitude than a certain threshold. The
threshold refers to the reduced coupling constant K in SI units (not
default). Additionally, an analysis in terms of Boys localized MOs (see
User's Guide and SFOs. At present, either each key LMO,
SFO, LMO2, SFO2 can be used individually, or grouped as {LMO, SFO2} or
{SFO2, LMO}. If you need all analyses or different combinations, it is
recommended to restart the CPL calculation from TAPE13, and to specify 0
iterations in the SCF. This way, the only additional computational cost
should be the analysis itself.
The equation and an application for the analyses due to the LMO and SFO keys is described in the papers Autschbach, J.; Igna, C. D.; Ziegler, T., A theoretical investigation of the apparently irregular behavior of Pt-Pt spin-spin coupling constants. J. Am. Chem. Soc. 2003, 125, 1028-1032, and Guennic, B. L.; Matsumoto, K.; Autschbach, J., On the NMR properties of platinum thallium bonded complexes: Analysis of relativistic density functional theory results. Magn. Res. Chem. 2004, 42, S99-S116. The other analysis is based on the same equation as in Khandogin, J.; Ziegler, T., A density functional study of nuclear magnetic resonance spin-spin coupling constants in transition metal systems. Spectrochim. Acta 1999, A 55, 607-624.
In order for the LMO-based analyses to work, the MO -> LMO transformation matrix needs to be stored on TAPE21. In the ADF input, you can achieve this with the option "STORE" to the LOCORB key, i.e.
LOCORB STORE ... options END
