ReSpect program

field

Specify an applied external electric field. In pump-probe simulations, this field refers to the first (pump) field.

Input block

Extended variant

field:

model: [formatted-string]

amplitude: [real]

inittime: [real]

width: [real]

frequency: [real]

direction: [x] [y] [z]

Default

none

Example

field: 
       model:      delta
       amplitude:  0.02 
       inittime:   12.9
       width:      25.8
       frequency:  0.37
       direction:  0.0  1.0  0.0

field2

Specify an applied external electric field. In pump-probe simulations, this field refers to the second (probe) field.

Input block

Extended variant

field2:

model: [formatted-string]

amplitude: [real]

inittime: [real]

width: [real]

frequency: [real]

direction: [x] [y] [z]

Default

none

Example

field: 
       model:      delta
       amplitude:  0.02 
       inittime:   12.9
       width:      25.8
       frequency:  0.37
       direction:  0.0  1.0  0.0

mowindow

Enable the selective perturbation (SP) approach introduced in Kadek et al. PCCP 17, 22566 (2015). SP enables to represent the perturbation and response operators only in selected molecular orbitals, allowing thus to address a specific spectral region in RT-TDSCF simulations, as well as to eliminate nonphysical excitations that are artifacts of the finite basis representation. This keyword is very important for core-level spectroscopies.

Input block

Extended variant

mowindow:

occupied: [intial-mo-index] - [final-mo-index]

virtual:  [intial-mo-index] - [final-mo-index]

Default

none

Example

mowindow:
         occupied:   4-6

mowindow:
         occupied:   7-10
         virtual:   15-46

Note

By default, the entire orbital spectrum is considered.

Occupied and virtual orbitals must be within their respective range. The range for occupied orbitals is from 1 to HOMO, whereas the range for virtual orbitals is from HOMO+1 to the total number of MOs.

Tip

SP turns out to be particularly useful for X-ray spectroscopies, where excitations occur only from specific core-shell orbitals. Here, we recommed to select for perturbation only the core-shell occupied MOs.

transition-analysis

Enable the transition density matrix analysis (TDMA) introduced in Repisky et al. JCTC 11, 980 (2015). TDMA enables to perform the orbital analysis of spectral transitions in RT-TDSCF simulations.

Input block

Extended variant

transition-analysis:

occupied: [intial-mo-index] - [final-mo-index]

virtual:  [intial-mo-index] - [final-mo-index]

threshold: [real]

Default

none

Example

transition-analysis:
         occupied:   8-10
         virtual:   11-25
         threshold: 1.0e-5

Note

By default, TDMA is disabled.

Occupied and virtual orbitals must be within their respective range. The range for occupied orbitals is from 1 to HOMO, whereas the range for virtual orbitals is from HOMO+1 to the total number of MOs.

Tip

Since TDMA may lead to an extensive data printout, we recommend to select only those orbitals relevant for the spectroscopy of interest.

spectroscopy

Specify the spectroscopy of interest.

Input line

spectroscopy:
                               
                                  
[string]

Default

none

Example

spectroscopy: eas

spectroscopy: ecd

spectroscopy: eas+ecd

time-steps

Define the time propagation details.

Input line

time-steps:
                               
                                  
[number-time-steps] x [time-step-length]

Default

none

Example

time-steps: 5000 x 0.05

solver

Specify the type of propagator used to solve the Liouville−von Neumann equation.

Input line

Default

solver: magnus

Example

solver: magnus

maxiterations

Define the maximum number of micro-iterations (per time step) for the Magnus solver.

Input line

maxiterations:
                               
                                  
[integer]

Default

maxiterations: 8

Example

maxiterations: 5

convergence

Define the convergence threshold for the Magnus solver.

Input line

convergence:
                               
                                  
[real]

Default

convergence: 1.0e-07

Example

convergence: 1.0e-5

checkpoint

Define the frequency of data checkpointing during the time propagation.

Input line

checkpoint:
                               
                                  
[integer]

Default

checkpoint: 100

Example

checkpoint: 500

[string]	description
eas	electron absorption spectroscopy (EAS), both in the valence and X-ray region
ecd	electronic circular dichroism (ECD), both in the valence and X-ray region
eas+ecd	evaluate the time-dependent spectral function for both EAS and ECD spectroscopy from a single run

[string]	description
magnus	Magnus propagator with a self-consistent extrapolation-interpolation scheme

[formatted-string]	description
delta	Dirac's delta function applied at time zero (recommended)
gauss	non-normalized Gaussian function with a half width \(\sigma\) and a time origin \(t_0\) $$ f(t_0,\sigma) = e^{-(t-t_{0})^2/({\sigma}^{2}/2)} $$ Both \(t_0\) and \(\sigma\) should be provided in atomic units by keywords "inittime" and "width".
cos	cosine function with an angular frequency \(\omega\) and a time origin \(t_0\) $$ f(t_0,\omega) = \cos[\omega(t-t_0)] $$ Both \(t_0\) and \(\omega\) should be provided in atomic units by keywords "inittime" and "frequency".
ecos	cosine function with an angular frequency \(\omega\) and a time origin \(t_0\), enveloped by a linear function in the first period $$ 0 \lt t-t_0 \lt \frac{2\pi}{\omega}:~~f(t_0,\omega) = \frac{\omega}{2\pi} (t-t_0) \cos[\omega(t-t_0)] $$ Outside of the period, the field is $$ t-t_0 \le 0:~~f(t_0,\omega) = 0; \qquad t-t_0 \ge \frac{2\pi}{\omega}:~~f(t_0,\omega) = \cos[\omega(t-t_0)]$$ Both \(t_0\) and \(\omega\) should be provided in atomic units by keywords "inittime" and "frequency".
gsin	sine function with an angular frequency \(\omega\), enveloped by a Gaussian function with a half width \(\sigma\) and a time origin \(t_0\) $$ f(t_0,\omega) = e^{-(t-t_{0})^2/({\sigma}^{2}/2)} \sin[\omega t] $$ The parameters \(t_0\), \(\sigma\), and \(\omega\) should be provided in atomic units by keywords "inittime", "width", and "frequency".
cos2	sine function with an angular frequency \(\omega\), enveloped by a cosine-squared function with a time origin \(t_0\) and a width \(\sigma\) $$ -{\sigma}/2 \le t-t_0 \le {\sigma}/2:~~f(t_0,\sigma,\omega) = \cos^{2}[\pi(t-t_0)/{\sigma}] \sin[\omega t] $$ Outside of the envelope, the field is zero, i.e. $$ t-t_0 \lt -{\sigma}/2:~~f(t_0,\sigma,\omega) = 0; \qquad t-t_0 \gt +{\sigma}/2:~~f(t_0,\sigma,\omega) = 0 $$ The parameters \(t_0\), \(\sigma\), and \(\omega\) should be provided in atomic units by keywords "inittime", "width", and "frequency".

[formatted-string]	description
delta	Dirac's delta function applied at time zero (recommended)
gauss	non-normalized Gaussian function with a half width \(\sigma\) and a time origin \(t_0\) $$ f(t_0,\sigma) = e^{-(t-t_{0})^2/({\sigma}^{2}/2)} $$ Both \(t_0\) and \(\sigma\) should be provided in atomic units by keywords "inittime" and "width".
cos	cosine function with an angular frequency \(\omega\) and a time origin \(t_0\) $$ f(t_0,\omega) = \cos[\omega(t-t_0)] $$ Both \(t_0\) and \(\omega\) should be provided in atomic units by keywords "inittime" and "frequency".
ecos	cosine function with an angular frequency \(\omega\) and a time origin \(t_0\), enveloped by a linear function in the first period $$ 0 \lt t-t_0 \lt \frac{2\pi}{\omega}:~~f(t_0,\omega) = \frac{\omega}{2\pi} (t-t_0) \cos[\omega(t-t_0)] $$ Outside of the period, the field is $$ t-t_0 \le 0:~~f(t_0,\omega) = 0; \qquad t-t_0 \ge \frac{2\pi}{\omega}:~~f(t_0,\omega) = \cos[\omega(t-t_0)]$$ Both \(t_0\) and \(\omega\) should be provided in atomic units by keywords "inittime" and "frequency".
gsin	sine function with an angular frequency \(\omega\), enveloped by a Gaussian function with a half width \(\sigma\) and a time origin \(t_0\) $$ f(t_0,\omega) = e^{-(t-t_{0})^2/({\sigma}^{2}/2)} \sin[\omega t] $$ The parameters \(t_0\), \(\sigma\), and \(\omega\) should be provided in atomic units by keywords "inittime", "width", and "frequency".
cos2	sine function with an angular frequency \(\omega\), enveloped by a cosine-squared function with a time origin \(t_0\) and a width \(\sigma\) $$ -{\sigma}/2 \le t-t_0 \le {\sigma}/2:~~f(t_0,\sigma,\omega) = \cos^{2}[\pi(t-t_0)/{\sigma}] \sin[\omega t] $$ Outside of the envelope, the field is zero, i.e. $$ t-t_0 \lt -{\sigma}/2:~~f(t_0,\sigma,\omega) = 0; \qquad t-t_0 \gt +{\sigma}/2:~~f(t_0,\sigma,\omega) = 0 $$ The parameters \(t_0\), \(\sigma\), and \(\omega\) should be provided in atomic units by keywords "inittime", "width", and "frequency".

Latest Posts

Webpage update

July 17, 2024

Program update: ReSpect 5.3.0

July, 2024

Latest Publications

Book chapter on relativistic real-time electron dynamics

May, 2024

Book chapter on relativistic theory of EPR and (p)NMR

May, 2024

Useful Links

Our Contacts

Hylleraas Centre
Department of Chemistry
UiT The Arctic University of Norway
Tromsø, NO-9037 Norway
Email: info@respectprogram.eu

field

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field2

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mowindow

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Note

Tip

transition-analysis

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Note

Tip

spectroscopy

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time-steps

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solver

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maxiterations

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convergence

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checkpoint

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Latest Posts

Webpage update

Program update: ReSpect 5.3.0

Latest Publications

Book chapter on relativistic real-time electron dynamics

Book chapter on relativistic theory of EPR and (p)NMR

Useful Links

Our Contacts