ReSpect program

xc

Specify details associated with the evaluation of the exchange–correlation (xc) kernel.

Input block

Short variant

xc: 
                                         
                                            
                                               
                                                
                                               
                                               
                                                  
                                                     
[functional]

Extended variant

xc:

functional: [functional]

noncollinearity: [string]

Default

xc:
  functional      : from-scf
  noncollinearity : v2005

Example

xc: XALDA

xc:
     functional      : XALDA
     noncollinearity : v2019

Warning

The use of ALDA or XALDA options is not recommended, because they usually approximate the full xc kernel. Their use is only recommended when comparing the calculated data to implementations in other quantum chemistry programs, where those approximations can not be avoided.

eri

Specify details associated with the evaluation of electron repulsion integrals (ERI) and related two-electron Fock contributions.

Input block

Short variant

Extended variant

eri:

class: [string]

threshold: [real]

acceleration: [string]

Default

Default is taken from the scf step of the calculation.

Example

eri: ri-j

eri:
   class:        ssss/abcd 
   threshold:    1.e-15
   acceleration: ri-j

analysis

Analyze contributions from molecular orbitals to the paramagnetic part of the NMR shielding tensor.

Input block

Short variant

Extended variant

analysis:

analyze: [analyze]

xyz-values: [string]

sort: [boolean]

sort-by: [string]

occ-threshold: [real]

vir-threshold: [real]

energy-degeneracy: [real]

output-digits: [integer]

Default

analysis:
     analyze           : none
     xyz-values        : principal
     sort              : True
     sort-by           : iso
     occ-threshold     : 0.1
     vir-threshold     : 0.1
     energy-degeneracy : 1.0e-8
     output-digits     : 2

Example

analysis:
     analyze       : MO
     xyz-values    : diagonal
     sort          : False
     sort-by       : x
     occ-threshold : 0.01
     vir-threshold : 0.01

diis

Specify setting of DIIS (direct inversion in the iterative subspace) scheme.

Input block

Short variant

Extended variant

diis:

start: [integer]

collect: [integer]

maximum: [integer]

Default

diis:
  start   : 1
  collect : 3
  maximum : 30

Example

diis: on

g-factor

Specify the nuclear g-factor.

Input block

Extended variant

g-factor:

[element-symbol]: [integer]

[element-index]: [integer]

...

Default

G-factor of isotopes with largest abundance and non-zero spin.

Example

g-factor:
   H : 5.5856947
   2 : 0.8574382
   C : 1.4048236

Note

Although NMR shielding tensor is calculated only for elements with non-zero g-factor (see Tip below), the actual result does not depend on the g-factor value.

The data in the g-factor block is processed line by line, therefore the latter data overwrites the former one.

Data from g-factor block overwrites setting from the isotope block.

Tip

NMR shielding tensor is calculated only for NMR active atoms (non-zero g-factor). This keyword can be used to set non-zero g-factor for elements witch isotopes have only zero or unknown magnetic moment to perform hypothetical studies (like f.e. At).

grid

Specify atomic grids for the numerical evaluation of exchange-correlation DFT contributions.

Input block

Short variant

Extended variant

grid:

all: [string]

[element-symbol]: [string]

[element-index]: [string]

...

Default

Grid defaults are taken from the SCF section.

Example

grid: large

grid:
     C: medium
     7: large

Note

There can be multiple instances of [element-symbol] and [element-index] in the grid block.

While lines in the grid block can be mixed, they are always processed in the following order: "all", "element-symbol", and "element-index" keywords.

The order of processing the data matters, since the latter lines rewrite the data of the former lines. This way one can easily set the same grid for all carbons except the carbon number 7 (see example).

auxbas

Specify atomic auxiliary basis sets.

Input block

Short variant

auxbas: 
                                         
                                            
[basis-name]

Extended variant

auxbas:

all: [basis-name]

[element-symbol]: [basis-name]

[element-index]: [basis-name]

...

Default

none

Example

In this example, auxiliary ucc-pvtz basis is assigned to all elements.

auxbas: ucc-pvtz

In this example, upc-2 basis is assigned to the 4th element (as specified in the input block "geometry") and dyall-vtz basis to all bromine atoms.

auxbas:
   4:  upc-2
   Br: dyall-vtz

Note

The use of auxiliary basis makes sense only in connection with an approximative evaluation of electron repulsion integrals (ERI) by means of the resolution-of-identity (RI) technique. This is controlled by the keyword "acceleration" in the "eri" block.

In the case of missing definition of auxiliary basis, the program will assign the basis automatically based on the chosen orbital basis, provided the orbital basis was selected from the internal program library.

gauge

Options for solving the gauge origin problem.

Input line

gauge:
                               
                                  
[formatted-string]

Default

gauge: giao

Example

gauge: atom 2

gauge: center-of-mass

active-atoms

Specify atoms for the calculation of NMR shielding tensor.

Input line

active-atoms:
                               
                                  
[formatted-string]

Default

active-atoms: all

Example

active-atoms: H

active-atoms: 5, C, 1-3

print-level

Set the amount of information printed in the output file.

Input line

print-level:
                               
                                  
[string]

Default

print-level: normal

Example

print-level: long

convergence

Convergence threshold for the self-consistent procedure.

Input line

convergence:
                               
                                  
[real]

Default

convergence: 1.0e-5

Example

convergence: 1.0e-3

dmixing

Mixing parameter for the self-consistent procedure.

Input line

Default

dmixing: 1.0e0

Example

dmixing: 0.2e0

maxiterations

Maximum number of iterations for the self-consistent procedure.

Input line

maxiterations:
                               
                                  
[integer]

Default

maxiterations: 30

Example

maxiterations: 20

nc-model

Model for the charge distribution of nucleus.

Input line

Default

nc-model: point

Example

nc-model: gauss

nmm-model

Model for the magnetic moment distribution of nucleus.

Input line

nmm-model:
                               
                                  
[string]

Default

nmm-model: point

Example

nmm-model: gauss

magnetic-field

Orientation of the external magnetic field perturbation.

Input line

magnetic-field:
                               
                                  
[string]

Default

magnetic-field: xyz

Example

magnetic-field: x

Tip

Combine keywords response-only and magnetic-field to speed up calculation, if you are (f.e.) interested only in the visualization of certain component of magnetically induced current density.

response-only

It allows to calculate only response molecular orbitals.

Input line

response-only:
                               
                                  
[boolean]

Default

response-only: False

Example

response-only: True

Tip

Combine keywords response-only and magnetic-field to speed up calculation, if you are (f.e.) interested only in the visualization of certain component of magnetically induced current density.

contribution

Calculate selected contribution to the NMR shielding tensor within four-component CGO method.

Input line

contribution:
                               
                                  
[string]

Default

contribution: all

Example

contribution: L;PSO

contribution: S;FC

spin-orbit

Calculate the spin-orbit contribution to the non-relativistic NMR shielding tensor within CGO method. This keyword is recommended to use only in conjunction with "analysis" keyword (see the Warning message).

Input line

spin-orbit:
                               
                                  
[boolean]

Default

spin-orbit: False

Example

spin-orbit: True

Warning

The purpose of this keyword is to perform molecular orbital analysis of the spin-orbit contribution to the paramagnetic part of the NMR shielding tensor. It is NOT recommended to use it for practical calculations since it captures only portion of relativistic effects and does not accommodate London atomic orbitals.

[formatted-string]	description
giao	Gauge including atomic orbitals (recommended).
atom [integer]	Set the gauge on the atom number [integer], where [integer] is the index of the atom in the molecular geometry.
coordinates-origin	Set the gauge on the origin of the coordinate system.
center-of-mass	Set the gauge on the center of mass of the system.
point [x] [y] [z]	Define the gauge as Cartesian coordinates in atomic units.

[formatted-string]	description
all	Select all NMR active atoms (with non-zero g-factor).
[N], [M], ...	Specify a set of atoms separated by comma. Use either geometry index of the atom (including dash separated range) or atom label.

[string]	description
normal	Standard amount of information (recommended).
long	Additional information is printed in the .out file (may clog the output).
debug	New .dbg file will be created with even more information (mostly used for debugging purposes).
long-debug	New .dbg file will be created with potentially huge amount of information (it is feasible only for small systems).

[string]	description
from-scf	Model for the nuclear charge distribution is taken from scf step.
point	Point distribution of the nuclear charge.
gauss	Finite distribution of the nuclear charge.

[string]	description
point	Point distribution of the nuclear magnetic moment.
gauss	Finite distribution of the nuclear magnetic moment.

[string]	description
xyz	Calculate all three sets of response molecular orbitals.
x	Calculate only x component of magnetic response MOs.
y	Calculate only y component of magnetic response MOs.
z	Calculate only z component of magnetic response MOs.

[string]	description
all	Perform the standard non-relativistic or relativistic calculation.
[X];[Y]	Combination of X and Y operators is used in the four-component NMR shielding calculation, where X is one of L,S,REL and Y one of FC,SD,PSO,REL.

[functional]	description
xalda	Uses SVWN5 functional for the exchange-correlation kernel, regardless of the type of the xc functional in the scf step. Full Hartree–Fock kernel is calculated with the percentage of the exchange admixture taken from the scf step.
alda	Uses SVWN5 functional for the exchange-correlation kernel, regardless of the type of the xc functional in the scf step. The Hartree–Fock exchange kernel is omitted even if the scf step was calculated using hybrid functional. Note that the Coulomb part of the Hartree–Fock kernel is not omitted. This is relevant for the open-shell calculation where Coulomb part is nonzero.
from-scf	Functional for calculation of the xc kernel matches the functional from the scf step.

[string]	description
v2005	The 2005 version of the noncollinear xc kernel has both numerical and analytical form. The numerical formulation of the xc noncollinear scheme for closed-shell reference state was for the first time presented in ref [Komorovsky2008], while its analytical formulation was presented later in ref [Komorovsky2015]. In the case of open-shell reference state the noncollinear xc kernel can be calculated numerically (for the first time presented in ref [Komorovsky2013]) or analytically using (X)ALDA approximation. The numerical form is derived from the open-shell noncollinear xc potential which was for the first time used for the calculation of g-tensor at two-component level [Malkin2005]. The implementation details of this noncollinear xc potential can be found in reference ReSpect article [Repisky2020] in eq (68). Note that in the numerical evaluation of the xc kernel one calculates numerical derivative of the xc potential with the numerical parameter being the external magnetic field. The numerical evaluation of the xc kernel was abandoned in 2015. The implementation details of the analytical form of the 2005 version of the noncollinear xc kernel is summarized in Table III in ref [Repisky2020] labeled with superscript d. These versions of the noncollinear scheme were used in all ReSpect calculations till 2019. The notable disadvantage of the 2005 version of the noncollinear xc kernel is restriction of the analytical form for open-shell calculations to (X)ALDA approximation and inconsistency of the numerical and analytical formulation discussed in ref [Repisky2020] section II.E (i.e. inconsistency of the xc potential and kernel) I. Malkin, O. L. Malkina, V. G. Malkin, and M. Kaupp, J. Chem. Phys. 123, 244103 (2005) S. Komorovsky, M. Repisky, O. L. Malkina, V. G. Malkin, I. Malkin-Ondik, and M. Kaupp, J. Chem. Phys. 128, 104101 (2008) S. Komorovsky, M. Repisky, K. Ruud, O. L. Malkina, and V. G. Malkin, J. Phys. Chem. A 117, 14209–14219 (2013) S. Komorovsky, M. Repisky, E. Malkin, T. B. Demissie, K. Ruud, J. Chem. Theory Comput. 11, 3729–3739 (2015) M. Repisky, S. Komorovsky, M. Kadek, L. Konecny, U. Ekstrom, E. Malkin, M. Kaupp, K. Ruud, O. L. Malkina, and V. G. Malkin, J. Chem. Phys. 152, 184101 (2020)
v2019	The 2019 version of the noncollinear xc kernel for both open- and closed-shell systems have been published in the framework of LR-TDDFT [Komorovsky2019]. This is the most general formulation of the noncollinear scheme and can be used for prediction of all spectroscopic parameters available in the ReSpect. The xc potential and kernel is formulated in the analytic form. The closed-shell limit of the open-shell noncollinear scheme corresponds to the xc kernel for the first time presented in ref [Bast2009]. In the output files we refer to closed-shell and open-shell formulation of the noncollinear xc scheme as WB2009 and WSK2019, respectively. WB2009: [Wang2004] + [Bast2009] WSK2019: [Wullen2002] + [Scalmani2012] + [Komorovsky2019] The implementation details of the 2019 version of the noncollinear xc kernel is summarized in Table III in reference ReSpect article [Repisky2020] labeled as recommended option (superscript b). C. Van Wüllen, J. Comput. Chem. 23, 779–785 (2002) F. Wang and T. Ziegler, J. Chem. Phys. 121, 12191 (2004) R. Bast, H. J. A. Jensen, and T. Saue, Int. J. Quant. Chem. 109, 2091–2112 (2009) G. Scalmani and M. J. Frisch, J. Chem. Theory Comput. 8, 2193–2196 (2012) S. Komorovsky, P. Cherry, and M. Repisky, J. Chem. Phys. 151, 184111 (2019) M. Repisky, S. Komorovsky, M. Kadek, L. Konecny, U. Ekstrom, E. Malkin, M. Kaupp, K. Ruud, O. L. Malkina, and V. G. Malkin, J. Chem. Phys. 152, 184101 (2020)

[string]	description
llll	evaluate only the [LL\|LL] class (default for one- and two-component Hamiltonians)
ssll/abcd	evaluate exactly [LL\|LL], [LL\|SS] and [SS\|LL] classes but neglect [SS\|SS]
ssss/aabb	evaluate exactly [LL\|LL], [LL\|SS] and [SS\|LL] classes and use an one-center approximation for [SS\|SS]. In this approximation, both functions in [SS\| and \|SS] should share the same atomic center, otherwise they are excluded from evaluation. This is the default for four-component Hamiltonians.
ssss/abcd	evaluate exactly all four ERI classes

[string]	description
ri-j	resolution-of-identity (RI) for the two-electron Coulomb term
none	no approximation imposed

[eri]	description
ri-j	resolution-of-identity (RI) for the two-electron Coulomb term
exact	exact evaluation of four-center two-electron integrals

[analyze]	description
MO	Analyze molecular orbital (MO) contributions to the paramagnetic part of the NMR shielding tensor.
none	Skip analysis.

[string]	description
principal	Transform tensor of each MO contribution to principal axes of the total NMR shielding tensor. As a result x, y and z components of each MO contribution directly contribute to the principal values of the total NMR shielding tensor.
diagonal	Analyze diagonal components of the MO contribution tensor. WARNING: As a result of this analysis, x, y and z component of the MO tensor does not in general directly contribute to the principal values of the total NMR shielding tensor.

[string]	description
iso	Only contributions with the modulus of isotropic value larger then threshold are printed to output.
x	Only contributions with the modulus of x (principal) tensor component larger then threshold are printed to output.
y	Only contributions with the modulus of y (principal) tensor component larger then threshold are printed to output.
z	Only contributions with the modulus of z (principal) tensor component larger then threshold are printed to output.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[basis-name]	description
basis-name	List of available basis sets can be found here: url-basis

[basis-name]	description
basis-name	List of available basis sets can be found here: url-basis

[basis-name]	description
basis-name	List of available basis sets can be found here: url-basis

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Webpage update

July 17, 2024

Program update: ReSpect 5.3.0

July, 2024

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Book chapter on relativistic real-time electron dynamics

May, 2024

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May, 2024

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