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 vibration_correlation_programs [2020/07/15 15:34]qianli vibration_correlation_programs [2022/01/14 15:04] (current)rauhutdennisdinu [Rovibrational calculations] 2022/01/14 15:04 rauhutdennisdinu [Rovibrational calculations] 2021/08/05 09:49 rauhutmathea [Options] 2021/07/28 13:35 rauhuterfort [Rovibrational calculations] 2021/07/28 12:25 rauhuterfort 2020/07/15 15:35 qianli 2020/07/15 15:34 qianli 2020/06/11 18:17 external edit 2022/01/14 15:04 rauhutdennisdinu [Rovibrational calculations] 2021/08/05 09:49 rauhutmathea [Options] 2021/07/28 13:35 rauhuterfort [Rovibrational calculations] 2021/07/28 12:25 rauhuterfort 2020/07/15 15:35 qianli 2020/07/15 15:34 qianli 2020/06/11 18:17 external edit Line 1: Line 1: ====== Vibration correlation programs ====== ====== Vibration correlation programs ====== - - [vibcorr] ===== The VCI program (VCI) ===== ===== The VCI program (VCI) ===== - ''VCI'',//options// [vci] + ''VCI'',//options// ''VCI'' calculations account for vibration correlation effects and use potential energy surfaces as generated from the ''SURF'' or ''XSURF'' programs and a basis of ''VSCF'' modals or harmonic oscillator functions. For each vibrational state an individual ''VCI'' calculation will be performed. As ''VCI'' calculations may require substantial computer resources, these calculations can be rather expensive. Currently, two different ''VCI'' programs (configuration selective and conventional) are available (see below). Moreover, VCI calculations can be performed using the grid-based version of the program or within an analytical representation. The latter is significantly faster and is thus recommended. The different versions of the configuration selection ''VCI'' program and the underlying configuration selection scheme are described in detail in:\\ ''VCI'' calculations account for vibration correlation effects and use potential energy surfaces as generated from the ''SURF'' or ''XSURF'' programs and a basis of ''VSCF'' modals or harmonic oscillator functions. For each vibrational state an individual ''VCI'' calculation will be performed. As ''VCI'' calculations may require substantial computer resources, these calculations can be rather expensive. Currently, two different ''VCI'' programs (configuration selective and conventional) are available (see below). Moreover, VCI calculations can be performed using the grid-based version of the program or within an analytical representation. The latter is significantly faster and is thus recommended. The different versions of the configuration selection ''VCI'' program and the underlying configuration selection scheme are described in detail in:\\ Line 21: Line 19: * **''CIMAX''=//value//** ''CIMAX'' is the maximum excitation level corresponding to ''CITYPE'' and ''LEVEX''. In principle, a triple configuration $(1^42^43^4)$ would contribute to the VCI space. However, ''CIMAX=7'' restricts this to $(1^42^3)$, $(1^32^33^1)$, $(1^32^23^2), ...$. The default is ''CIMAX=12'' for 3D potentials and ''CIMAX=15'' for 4D potentials. * **''CIMAX''=//value//** ''CIMAX'' is the maximum excitation level corresponding to ''CITYPE'' and ''LEVEX''. In principle, a triple configuration $(1^42^43^4)$ would contribute to the VCI space. However, ''CIMAX=7'' restricts this to $(1^42^3)$, $(1^32^33^1)$, $(1^32^23^2), ...$. The default is ''CIMAX=12'' for 3D potentials and ''CIMAX=15'' for 4D potentials. * **''CITYPE''=//n//** ''CITYPE'' defines the maximum number of simultaneous excitations, i.e. Singles, Doubles, Triples, ... and thus determines the kind of calculations, i.e. VCISD, VCISDT, ... The default is ''CITYPE=4'' (VCISDTQ) for 3D potentials and ''CITYPE=5'' for 4D potentials, which appears to be a fair compromise between accuracy and computational speed. The maximum excitation level is currently limited to ''CITYPE=9''. * **''CITYPE''=//n//** ''CITYPE'' defines the maximum number of simultaneous excitations, i.e. Singles, Doubles, Triples, ... and thus determines the kind of calculations, i.e. VCISD, VCISDT, ... The default is ''CITYPE=4'' (VCISDTQ) for 3D potentials and ''CITYPE=5'' for 4D potentials, which appears to be a fair compromise between accuracy and computational speed. The maximum excitation level is currently limited to ''CITYPE=9''. + * **''CLASSES''=//n//** CLASSES=1 allows for the rigorous use of the Slater-Condon rules by employing configuration classes in configuration selection and VCI matrix set-up. * **''CLCTYPE''=//n//** (=2 Default) All VCI programs are based on a real configuration basis. If the state of interest is specified by the $l$ quantum number (symmetric top or linear molecules) an appropriate start vector for the iterative eigenvalue solver will be generated automatically. The option ''CLCTYPE'' allows to use different start vectors. * **''CLCTYPE''=//n//** (=2 Default) All VCI programs are based on a real configuration basis. If the state of interest is specified by the $l$ quantum number (symmetric top or linear molecules) an appropriate start vector for the iterative eigenvalue solver will be generated automatically. The option ''CLCTYPE'' allows to use different start vectors. * **''COMBI''=//n//** By default the ''VSCF'' program calculates the fundamental modes of the molecule only. However, choosing ''COMBI=''$n$ allows for the calculation of the vibrational overtones and combination bands. The value of $n$ controls the excitation level, i.e. the number of states to be computed increases very rapidly for large values of $n$. Therefore, by default the upper limit is set to 5000 cm$^{-1}$, but this cutoff can be changed by the option ''UBOUND''. * **''COMBI''=//n//** By default the ''VSCF'' program calculates the fundamental modes of the molecule only. However, choosing ''COMBI=''$n$ allows for the calculation of the vibrational overtones and combination bands. The value of $n$ controls the excitation level, i.e. the number of states to be computed increases very rapidly for large values of $n$. Therefore, by default the upper limit is set to 5000 cm$^{-1}$, but this cutoff can be changed by the option ''UBOUND''. Line 44: Line 43: * **''SADDLE''=//n//** By default, i.e. ''SADDLE=0'', the ''VCI'' program assumes, that 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 the ''VCI'' program by using ''SADDLE=1''. Currently, the ''VCI'' program can only handle symmetrical double-minimum potentials. * **''SADDLE''=//n//** By default, i.e. ''SADDLE=0'', the ''VCI'' program assumes, that 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 the ''VCI'' program by using ''SADDLE=1''. Currently, the ''VCI'' program can only handle symmetrical double-minimum potentials. * **''SELSCHEME''=//n//** By default ''SELSCHEME''=1, configurationis will be selected by a perturbative criterion. Alternative one may use a criterion based on 2$\times$2 VCI matrices (''SELSCHEME''=2). Usually the differences are extremely small and the matrix based criterion is slightly more time-consuming. * **''SELSCHEME''=//n//** By default ''SELSCHEME''=1, configurationis will be selected by a perturbative criterion. Alternative one may use a criterion based on 2$\times$2 VCI matrices (''SELSCHEME''=2). Usually the differences are extremely small and the matrix based criterion is slightly more time-consuming. + * **''SKIPDIAG''=//n//** If SKIPDIAG=ITER with ITER>1 is set, the configuration selection based on a VMP2-like wavefunction is used after the ITERth iteration step, as long as the energy difference between the energy eigenvalues of the last  two iteration steps is less than THRDIAG (see below). SKIPDIAG=2 usually leads to appropriate results. + * **''SKIPSAVE''=//n//** In cases of small deviations with respect to the norm of the VMP2-like wavefunction, SKIPSAVE=1 may be used to further reduce the computational cost for configuration selection. Note, that renormalization is not possible anymore in this case. The default is SKIPSAVE=0 (disabled). + * **''SUBSPACE''=//n//** SUBSPACE=1 enables the use of prediagonalization of physically meaningful subspaces. * **''SYMBASIS''=//n//** The assignment of symmetry labels is realized by a projection operator. By default, the basis functions used are automatically determined. ''SYMBASIS=1'' switches to alternative basis functions. * **''SYMBASIS''=//n//** The assignment of symmetry labels is realized by a projection operator. By default, the basis functions used are automatically determined. ''SYMBASIS=1'' switches to alternative basis functions. * **''THERMO''=//n//** ''THERMO=1'' allows for the improved calculation of thermodynamical quantities (compare the ''THERMO'' keyword in combination with a harmonic frequency calculation). However, the approach used here is an approximation: While the harmonic approximation is still retained in the equation for the partition functions, the actual values of the frequencies entering into these functions are the anharmonic values derived from the ''VCI'' calculation. Default: ''THERMO=0''. * **''THERMO''=//n//** ''THERMO=1'' allows for the improved calculation of thermodynamical quantities (compare the ''THERMO'' keyword in combination with a harmonic frequency calculation). However, the approach used here is an approximation: While the harmonic approximation is still retained in the equation for the partition functions, the actual values of the frequencies entering into these functions are the anharmonic values derived from the ''VCI'' calculation. Default: ''THERMO=0''. * **''THRCF''=//value//** ''THRCF'' is the threshold for selecting individual configurations. The default is given by ''THRCF''=$5\cdot 10^{-10}$. * **''THRCF''=//value//** ''THRCF'' is the threshold for selecting individual configurations. The default is given by ''THRCF''=$5\cdot 10^{-10}$. + * **''THRDIAG''=//value//** The default is THRDIAG=1.0d0 (wavenumbers). THRDIAG gives the energy difference of the energy eigenvalues between two consecutive iterations. The VMP2-like wavefunction is employed for configuration selection if the respective energy difference is smaller than THRDIAG, i.e. VCI matrix diagonalizations/eigenvector determinations are omitted. + * **''THRECORR''=//value//** Convergence criterion in the case the VMP2-like wavefunction is used for configuration selection. If the sum of energy corrections given by the configurations selected in a specific iteration step is smaller than THRECORR, the final VCI matrix is set-up and the eigenvector is determined. The default is THRECORR=1.0d0 (wavenumbers). * **''THREX''=//value//** This thresholds controls the exclusion of selected configurations within the perturbative configuration selection criterion. The default is ''THREX=5.d-4''. * **''THREX''=//value//** This thresholds controls the exclusion of selected configurations within the perturbative configuration selection criterion. The default is ''THREX=5.d-4''. * **''THRSEL''=//value//** ''THRSEL'' controls the determination of the iterative configuration selection scheme. By default the wavefunction is considered to be converged once energy changes drop below ''THRSEL''=0.02 cm$^{-1}$. * **''THRSEL''=//value//** ''THRSEL'' controls the determination of the iterative configuration selection scheme. By default the wavefunction is considered to be converged once energy changes drop below ''THRSEL''=0.02 cm$^{-1}$. Line 69: Line 73: ''ROVIB'',//options// ''ROVIB'',//options// - By default, the ''VCI'' program calculates purely vibrational states only. However, the ''ROVIB'' directive allows for the calculation of rovibrational transitions for molecules with Abelian point groups. This includes also the IR intensities once dipole moment surfaces have been computed. For details see:\\ + By default, the ''VCI'' program calculates purely vibrational states only. However, the ''ROVIB'' directive allows for the calculation of rovibrational transitions for molecules with Abelian point groups. This includes also the IR intensities once dipole moment surfaces have been computed and Raman intensities if they are available and requested in the vibrational calculation. For details see:\\ S. Erfort, M. Tschoepe, G. Rauhut, //Towards a fully automated calculation of rovibrational infrared intensities for semi-rigid polyatomic molecules//, J. Chem. Phys. **153**, xxxxxx (2020).\\ S. Erfort, M. Tschoepe, G. Rauhut, //Towards a fully automated calculation of rovibrational infrared intensities for semi-rigid polyatomic molecules//, J. Chem. Phys. **153**, xxxxxx (2020).\\ The following //options// are available: The following //options// are available: - * **''HOTB''=//n//** (=0 (off) Default) The calculation of vibrational hot bands can be switched on with ''HOTB=1''. - * **''IRDAT''=//string//** File name for dumping the rovibrational infrared line list. Activates calculation of rovibrational intensities. - * **''IRUNIT''=//string//** The default unit for the IR intensities is km/mol. ''IRUNIT''=’HITRAN’ provides the results in HITRAN units, i.e. cm$^{-1}$/(molecule cm$^{-2}$). This key is only active in rovibrational calculations. * **''JMAX''=//n//** By default VCI 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. * **''JMAX''=//n//** By default VCI 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. - * **''%%JMAX\_PRINT%%''=//n//** (=min(Jmax,3) Default) This option controls the printout in rovibrational calculations, i.e. the maximum J value, up to which information shall be printed. + * **''%%JMAX_PRINT%%''=//n//** (=min(Jmax,3) Default) This option controls the printout in rovibrational calculations, i.e. the maximum J value, up to which information shall be printed. - * **''NSSW''=//string//** Sequence of nuclear spin statistical weights in the order of irreps commonly used in the character table for the current molecular point group, e.g. ’1-1-3-3’ for irreps A$_1$, A$_2$, B$_1$, B$_2$ in the case of H$_2$CO. + - * **''%%PARTF\_R\_THR%%''=//value//** (=$10^{-4}$ Default) Threshold for the relative deviation within the iterative determination of the rotational partition function. + - * **''%%PARTF\_V\_THR%%''=//value//** (=$10^{-2}$ Default) Threshold for the relative deviation within the iterative determination of the vibrational partition function. + - * **''RBAS''=//n//** (=1 Default) Definition of the rotational basis in rovibrational calculations.\\ + - ''RBAS=1'' refers to primitive rigid rotor states $|Jk>$.\\ + - ''RBAS=2'' a symmetrized rotational basis by employing Wang combination is used, i.e. $|J K \tau> = i^\sigma/\sqrt{2} (|JK> + (-1)^{J+K+\tau}|J-K>)$. + * **''RVINFO''=//n//** (=1 Default) Additional rovibrational output. By default this will print the nuclear spin statistical weights. ''RVINFO=2'' provides additional details on the calculation and assignment of nuclear spin statstical weights. ''RVINFO=3'' enables further integrals, etc. * **''RVINFO''=//n//** (=1 Default) Additional rovibrational output. By default this will print the nuclear spin statistical weights. ''RVINFO=2'' provides additional details on the calculation and assignment of nuclear spin statstical weights. ''RVINFO=3'' enables further integrals, etc. - * **''%%RVINT\_THR%%''=//value//** (=10$^{-2}$ Default) Threshold for printing rovibrational intensities. * **''RVMU''=//n//** This keyword controls the order of integrals arising from the inverse moment of inertia tensor $\mu_{\alpha\beta}$ within the calculation of the partition functions as needed in rovibrational calculations. By default a constant $\mu$-tensor is assumed. * **''RVMU''=//n//** This keyword controls the order of integrals arising from the inverse moment of inertia tensor $\mu_{\alpha\beta}$ within the calculation of the partition functions as needed in rovibrational calculations. By default a constant $\mu$-tensor is assumed. - * **''RVPRINT''=//n//** This keyword controls the rovibrational line list printout. ''RVPRINT=1'' prints the transition moments, ''RVPRINT=2'' the oscillator strengths, ''RVPRINT=3'' the Einstein A coefficients, ''RVPRINT=4'' symmetry information, and ''RVPRINT=5'' vibrational hot bands. Any of these numbers can be combined, e.g. ''RVPRINT=123'' prints the transition moments, the oscillator strengths and the Einstein A coefficients. This keyword or the ''IRDAT'' and/or ''RAMANDAT'' keyword have to be set in order for rovibrational intensitites to be computed. + * **''ENDAT''=//string//** File name for dumping the rovibrational energies. + * **''%%PARTF_R_THR%%''=//value//** (=$10^{-4}$ Default) Threshold for the relative deviation within the iterative determination of the rotational partition function. + * **''%%PARTF_V_THR%%''=//value//** (=$10^{-2}$ Default) Threshold for the relative deviation within the iterative determination of the vibrational partition function. * **''TINC''=//value//** (= 100 Default, in K) Temperature increment. * **''TINC''=//value//** (= 100 Default, in K) Temperature increment. * **''TLIST''=//string//** (off Default, in K) List of specific temperature values, e.g. ’300-350-400’. Combinable with other temperature-keywords. * **''TLIST''=//string//** (off Default, in K) List of specific temperature values, e.g. ’300-350-400’. Combinable with other temperature-keywords. * **''TMAX''=//value//** (=0 (off) Default, in K) Maximum temperature. Setting only ''TMIN'' will set ''TMAX'' to the same value. * **''TMAX''=//value//** (=0 (off) Default, in K) Maximum temperature. Setting only ''TMIN'' will set ''TMAX'' to the same value. * **''TMIN''=//value//** (=0 (off) Default, in K) Minimum temperature. Setting only ''TMAX'' will set ''TMIN'' to the same value. * **''TMIN''=//value//** (=0 (off) Default, in K) Minimum temperature. Setting only ''TMAX'' will set ''TMIN'' to the same value. + * **''RBAS''=//n//** (=1 Default) Definition of the rotational basis in rovibrational calculations. + * ''RBAS=1'' refers to primitive rigid rotor states $|Jk>$. + * ''RBAS=2'' a symmetrized rotational basis by employing Wang combination is used, i.e. $|J K \tau> = i^\sigma/\sqrt{2} (|JK> + (-1)^{J+K+\tau}|J-K>)$. + * **''NSSW''=//string//** Sequence of nuclear spin statistical weights in the order of irreps commonly used in the character table for the current molecular point group, e.g. ’1-1-3-3’ for irreps A$_1$, A$_2$, B$_1$, B$_2$ in the case of H$_2$CO. + * **''%%RVINT_THR%%''=//value//** (=10$^{-2}$ Default) Threshold for printing rovibrational intensities. + * **''RVPRINT''=//n//** This keyword controls the rovibrational line list printout. ''RVPRINT=1'' prints the transition moments, ''RVPRINT=2'' the oscillator strengths, ''RVPRINT=3'' the Einstein A coefficients, ''RVPRINT=4'' symmetry information, and ''RVPRINT=5'' vibrational hot bands. Any of these numbers can be combined, e.g. ''RVPRINT=123'' prints the transition moments, the oscillator strengths and the Einstein A coefficients. This keyword or the ''IRDAT'' and/or ''RAMANDAT'' keyword have to be set in order for rovibrational intensitites to be computed. + * **''DIP''=//n//** (=3 Default) Order of the $n$-mode expansion in the dipole surfaces used for vibrational transition moments in rovibrational intensities. + * **''POL''=//n//** (=3 Default) Order of the $n$-mode expansion in the polarizability surfaces used for vibrational transition moments in rovibrational intensities. + * **''HOTB''=//n//** (=0 (off) Default) The calculation of vibrational hot bands can be switched on with ''HOTB=1''. + * **''RAMAN_UBOUND_L''=//value//** Sets the upper energy bound for the lower state in rovibrational transitions. + * **''RAMAN_UBOUND_U''=//value//** Sets the upper energy bound for the upper state in rovibrational transitions. + * **''IRDAT''=//string//** File name for dumping the rovibrational infrared line list. Activates calculation of rovibrational intensities. + * **''IRUNIT''=//string//** The default unit for the IR intensities is km/mol. ''IRUNIT''=’HITRAN’ provides the results in HITRAN units, i.e. cm$^{-1}$/(molecule cm$^{-2}$). This key is only active in rovibrational calculations. + * **''RAMANDAT''=//string//** File name for dumping the rovibrational Raman line list. Activates calculation of rovibrational intensities. + * **''RAMAN_POLANG''=//value//** (=90 Default) Raman polarisation angle defining the prefactors mixing the isotropic and anisotropic Raman transition moments for the calculation of Raman intensities. + * **''RAMAN_FAC(n)''=//value//** Set the prefactors for the isotropic and anisotropic Raman transition moments for the calculation of Raman intensities manually. $n=0$ will set the value for $R_0$, $n=2$ the one for $R_2$. + * **''RAMAN_LFREQ''=//value//** (=680 Default, in nm) Raman exciting radiation (laser) frequency. + * **''PFIT''=//value//** (=0 Default) Fitting of spectroscopic parameters for asymmetric tops, using Watson's reduced operator. ''PFIT=1'' activates the fitting procedure if ''JMAX>0''. Intensities are not needed for the fitting. Currently, the spectroscopic parameters are fitted only with respect to the vibrational ground state. By setting ''PFIT=2'' or higher, additional printout is provided. + * **''PFITRED''=//A/S//** (=A Default) Select between A- and S-reduction. + * **''PFITDAT''=//string//** File name for dumping the term energies for the fitted spectroscopic parameters. + + + ==== Explicit definition of the correlation space ==== ==== Explicit definition of the correlation space ====