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vibrational_scf_programs [2020/06/11 18:17] – external edit 127.0.0.1 | vibrational_scf_programs [2022/08/16 14:15] (current) – external edit 127.0.0.1 | ||
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- | ====== Vibrational SCF programs ====== | + | ===== The VSCF programs (VSCF) ===== |

- | | + | |

- | ===== The VSCF program (VSCF) ===== | + | |

'' | '' | ||

The '' | The '' | ||

- | \begin{equation}\label{eq:} | + | \begin{align} |

\hat{H} = \frac{1}{2} \sum_{\alpha\beta} ( \hat{J}_\alpha - \hat{\pi}_\alpha) \mu_{\alpha\beta} | \hat{H} = \frac{1}{2} \sum_{\alpha\beta} ( \hat{J}_\alpha - \hat{\pi}_\alpha) \mu_{\alpha\beta} | ||

(\hat{J}_\beta - \hat{\pi}_\beta) | (\hat{J}_\beta - \hat{\pi}_\beta) | ||

-\frac{1}{8}\sum_\alpha \mu_{\alpha\alpha} -\frac{1}{2}\sum_i \frac{\partial^2}{\partial q_i^2} | -\frac{1}{8}\sum_\alpha \mu_{\alpha\alpha} -\frac{1}{2}\sum_i \frac{\partial^2}{\partial q_i^2} | ||

- | \end{equation} | + | \label{eq: |

+ | \end{align} | ||

in which the potential energy surfaces, $V(q_1, | in which the potential energy surfaces, $V(q_1, | ||

+ | J. Meisner, P.P. Hallmen, J. Kästner, G. Rauhut, // | ||

G. Rauhut, T. Hrenar, //A Combined Variational and Perturbational Study on the Vibrational Spectrum of P$_2$F$_4$//, | G. Rauhut, T. Hrenar, //A Combined Variational and Perturbational Study on the Vibrational Spectrum of P$_2$F$_4$//, | ||

- | The anharmonic frequencies and intensities calculated by the '' | ||

The following //options// are available: | The following //options// are available: | ||

- | * **''POT''variable//** VSCF solutions can be obtained using a potential in grid representation,. ''POT=GRID'', or in an analytical representation,. In the latter case the ''be called prior to the ''VSCF''in order to transform the potential. | + | * **''AVERAGE''n//** By default state-specific VSCF calculations will be performed. ''AVERAGE=1'' allows for configuration averaged VSCF calculations, i.e. CAVSCF. The averaging will be perfomed for those states being defined by the ''VIBSTATE''The vibrational ground state will alway be excluded. An identical weight factor will be used for all states, i.e. the inverse of the number of states. |

- | * **'', i.e. ''the ''the reference point of the potential belongs to a local minimum. Once the PES calculation has been started from a transition state, this information must be provided to ''. | + | * **''BASIS''variable//** ''BASIS=DGB''default) defines a mode-specific basis of distributed Gaussians and distributes the Gaussians in a way, that the overlap integral between two functions is always the same (controlled by ''THRBASOVLP''This guarantees that an increasing number of basis functions will always lead to an improvement. ''BASIS=HO'' defines a harmonic oscillator basis. Using this basis together with ''MAXITER=0''VAM=0'' provides a simple harmonic oscillator basis to be used in all subsequent programs, e.g. in the VCI program. ''BASIS=SIN'' uses a basis of sine functions. This is not a fully implemented feature, but primarily available for experimental purposes. |

- | * **''VAM''n//** The 0D terms of the vibrational angular momentum terms, i.e. $\frac{1}{2} \sum_{\alpha\beta} \hat{\pi}_\alpha\mu_{\alpha\beta} \hat{\pi}_\beta$,''VAM=2'') included.\\ | + | * **''DAT2GR program (DAT2GR)|the DAT2GR program (DAT2GR)]]) for even more possibilities of defining vibrational states. |

- | ''(see eq. \eqref{eq:) as a pseudo-potential like contribution to the fine grid of the potential.\\ | + | * **''DIPOLE''DIPOLE=1'' allows for the calculation of infrared intensities. Calculation of infrared intensities requires the calculation of dipole surfaces within the ''SURF'' program. By default the intensities will be computed on the basis of Hartree-Fock dipole surfaces. |

- | ''that the $\mu$ tensor is given as the inverse of the moment of inertia tensor at equilibrium geometry.\\ | + | |

- | When using ''(rather than the 0D term in case of ''VAM=2''Note that values higher than 2 are only active for non-linear molecules. ''VAM=5'' truncates the series after the 2D term. In almost all cases ''VAM=2'' is fully sufficient. Vibrational angular momentum terms are accounted for in a perturbational manner and do not affect the wavefunction. | + | |

- | * **''MUPLOT''=//n//** Plots all $\mu$-tensor surfaces up to //n//D and a corresponding Gnuplot script in a separate subdirectory (''. This option works only in combination with ''POT=POLY''The ''. | + | |

- | * **''VIBSTATE program (VIBSTATE)|the VIBSTATE program (VIBSTATE)]]) for even more possibilities of defining vibrational states. | + | |

- | * **''USERMODE''Once vibrational states have been defined with the ''''USERMODE=1''. Note that the vibrational ground state will always be computed and needs not to be specified explicitly. | + | |

- | * **''the upper energy limit is controlled by the keyword ''UBOND'', i.e. states, for which the harmonic estimate is larger than $n$, will not be computed. the default is set to $n$=5000 cm$^{-1}$. | + | |

- | * **''. | + | |

* **'' | * **'' | ||

- | * **''BASIS''variable//** ''BASIS=DGB'' (default) defines a mode-specific basis of distributed Gaussians and distributes the Gaussians in a way, that the overlap integral between two functions is always the same (controlled by ''of basis functions will always lead to an improvement. ''all subsequent programs, e.g. in the VCI program. ''. | + | * **''INFO''n//** ''INFO=1'' provides a list of the values of all relevant program parameters (options). |

- | * **''THRBASOVLP''value//** Overlap between two Gaussian basis functions, once ''=DGB''0.75. | + | * **''JMAX''n//** By default VSCF calculations will be performed for non-rotating molecules, i.e. J=0. Rovibrational levels can be computed for arbitrary numbers of J$=n$. This will perform a purely rotational calculation (RCI). To obtain approximate rovibrational energies, vibrational energies have to be added. |

- | * **''=//n//** Determines the type of orthogonalization within the VSCF program. ''a symmetrical orthogonalization,(see also keyword '' | + | |

- | * **''). The default is ''. | + | |

* **'' | * **'' | ||

- | * **''JMAX''By default VSCF calculations will be performed for non-rotating molecules, i.e. J=0. Rovibrational transitions can be computed for arbitrary numbers of J$=n$ within the adiabatic rotation approximation. | + | * **''MUPLOT''Plots all $\mu$-tensor surfaces up to //n//D and a corresponding Gnuplot script in a separate subdirectory (''plots''). This option works only in combination with ''POT=POLY''The ''VAM'' option has to be set accordingly. |

- | * **''//n//** ''(compare the ''THERMO'' keyword in combination with a harmonic frequency calculation). However, the approach used here is an approximation:''VSCF'' calculation. Default: ''THERMO=0'' | + | * **''NBAS''The number of basis functions (distributed Gaussians) to be used for solving the VSCF equations can be controlled by ''NBAS''. The default is ''NBAS=20''. This option is only active once an analytical representation of the potential has been chosen, see the option ''POT'''' |

- | * **''DIPOLE''''for the calculation of infrared intensities. Calculation of infrared intensities requires the calculation of dipole surfaces within the ''be computed on the basis of Hartree-Fock dipole surfaces. | + | |

- | * **''POLAR''** ''POLAR''=//1// allows to compute Raman intensities in addition to infrared intensities,of course requires polarizability tensor surfaces from the ''SURF''. By default Raman intensities are switched off. | + | |

* **'' | * **'' | ||

- | * **''are truncated. The default is set to 3. Note that '' | + | * **''shall be truncated. The default is set to 3. Note that '' |

- | * **''and must be smaller than 4. | + | * **'' |

- | * **''. | + | |

* **'' | * **'' | ||

+ | * **'' | ||

+ | * **'' | ||

+ | * **'' | ||

* **'' | * **'' | ||

- | * **''INFO''INFO=1'' provides a list of the values of all relevant program parameters (options). | + | * **''SADDLE''By default, i.e. ''SADDLE=0'',=1''. Currently, the '' |

+ | * **''a grid representation two different algorithms can be used. The default, i.e. ''of Young and Peet can be used ('' | ||

+ | * **''the improved calculation of thermodynamical quantities (compare the ''values of the frequencies entering into these functions are the anharmonic values derived from the '' | ||

+ | * **'' | ||

+ | * **'' | ||

+ | * **'' | ||

+ | * **''program (section [[vibrational SCF programs#)|the DAT2GR program (DAT2GR)]]), | ||

+ | * **'' | ||

+ | '' | ||

+ | '' | ||

+ | '' | ||

+ | When using ''. | ||

- | The following input example for a grid based calculation of anharmonic frequencies and intensities on the ''and (4) computes the nuclear wave function and the infrared intensities at the '' | + | The following input example for a grid based calculation of anharmonic frequencies and intensities on the '', (4) transforms the grid points to polynomials and (5) computes the nuclear wave function and the infrared intensities at the '' |

< | < | ||

Line 64: | Line 65: | ||

mp2 | mp2 | ||

optg !(1) optimizes the geometry | optg !(1) optimizes the geometry | ||

- | frequencies, !(2) compute harmonic frequencies | + | frequencies, !(2) compute harmonic frequencies |

label1 | label1 | ||

Line 72: | Line 73: | ||

cphf,1} | cphf,1} | ||

- | {surf,, !(3) generate potential energy surface | + | {xsurf, !(3) generate potential energy surface |

| | ||

- | vscf !(4) do a VSCF calculation | + | poly !(4) transform to polynomials |

- | put,irspec,!writes a gnuplot file to plot an IR | + | vscf,pot=poly !(5) do a VSCF calculation |

- | VSCF calculation | + | |

</ | </ | ||

- | ==== Record handling ==== | ||

- | |||

- | '' | ||

- | |||

- | The '' | ||

- | |||

- | The following //options// are available: | ||

- | |||

- | * **'' | ||

- | * **'' | ||

- | * **'' | ||

- | * **'' | ||

- | |||

- | ===== The VMCSCF program (VMCSCF) ===== | ||

- | |||

- | '' | ||

- | |||

- | The '' | ||

- | S. Heislbetz, G. Rauhut, // | ||

- | S. Heislbetz, F. Pfeiffer, G. Rauhut, // | ||

- | P. Meier, D. Oschetzki, F. Pfeiffer, G. Rauhut, //Towards an automated and efficient calculation of resonating vibrational states based on state-averaged multiconfigurational approaches//, | ||

- | |||

- | The following //options// are available: | ||

- | |||

- | Is the number of active modals for each mode. The smallest meaningful value for '' | ||

- | |||

- | Is the number of modals on top of the number of active modals. The default is '' | ||

- | |||

- | By default state-specific VMCSCF calculations will be performed. This may be altered by '' | ||

- | |||

- | Specifies, if only active-virtual modal rotations shall be considered ('' | ||

- | |||

- | The procedure how to determine the rotational angles between the modals within the Jacobi rotations can be specified by this keyword. '' | ||

- | |||

- | Once vibrational states have been defined with the '' | ||

- | |||

- | By default configuration-selective VMCSCF calculations will be performed ('' | ||

- | |||

- | Defines the maximum number of simultaneous excitations within the configurations generated from modals of the active space, i.e. Singles, Doubles, Triples, ... The maximum excitation level is limited to '' | ||

- | |||

- | '' | ||

- | |||

- | By default all VMCSCF calculations are based on ground-state based VSCF modals, '' | ||

- | |||

- | Controls the maximum number of macroiterations of the VMCSCF program. The default is 25. | ||

- | |||

- | Controls the convergence threshold for the macroiterations of the VMCSCF program. The default is 1.d-2. | ||

- | |||

- | Controls the maximum number of microiterations of the VMCSCF program. The default is 50. | ||

- | |||

- | Controls the convergence threshold for the microiterations of the VMCSCF program. The default is 1.d-5. | ||

- | |||

- | Provides additional information within the VMCSCF iterations, once a value larger than 0 (default) is used. | ||

- | |||

- | Specifies the record and file, on which the VMCSCF wave function shall be stored. The default is 5950.2. | ||

- | |||

- | Once set to 1, this option allows to store the VMCSCF modals in the record of the VSCF modals (which will be overwritten). This allows for VCI calculations with VMCSCF modals. | ||

- | |||

- | Besides these VMCSCF specific keywords, a number of option can be used, which are identical with those provided for the VCI program. These keywords are '' | ||

- | |||

- | ==== Explicit definition of active spaces ==== | ||

- | |||

- | '' | ||

- | Within the VMCSCF program the active space can be specified in a general manner (option '' | ||

- | |||

- | * **'' | ||

- | * **'' | ||

- | |||

- | ===== The VIBSTATE program (VIBSTATE) ===== | ||

- | |||

- | '' | ||

- | |||

- | The '' | ||

- | |||

- | ==== Definition of vibrational states ==== | ||

- | |||

- | '' | ||

- | This directive specifies the occupation number vector of the vibrational state to be calculated. | ||

- | |||

- | * **'' | ||

- |