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pes_transformations [2025/01/15 12:47] – rauhutpes_transformations [2025/05/22 09:29] (current) – rauhut
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   * **''NDIMDIP''=//n//** Term after which the $n$-body expansions of the dipole surfaces are truncated. The default is set to 3. Note that ''NDIMDIP'' has to be lower or equal than ''NDIM''.   * **''NDIMDIP''=//n//** Term after which the $n$-body expansions of the dipole surfaces are truncated. The default is set to 3. Note that ''NDIMDIP'' has to be lower or equal than ''NDIM''.
   * **''NDIMPOL''=//n//** Term after which the $n$-body expansions of the polarizability tensor surfaces are truncated. The default is 0. ''NDIMPOL'' has to be lower or equal than ''NDIM'' and must be smaller than 4.   * **''NDIMPOL''=//n//** Term after which the $n$-body expansions of the polarizability tensor surfaces are truncated. The default is 0. ''NDIMPOL'' has to be lower or equal than ''NDIM'' and must be smaller than 4.
 +  * **''NDIMQUAD''=//n//** Term after which the $n$-body expansions of the quadrupole tensor surfaces are truncated. The default is 0. ''NDIMQUAD'' has to be lower or equal than ''NDIM'' and must be smaller than 4.
   * **''NDIMMU''=//n//** An n-mode expansion of the $\mu$-tensor will be generated and transformed to polynomials up to 3rd order (default). The order can be changed by the integer passed to the ''NDIMMU'' keyword.   * **''NDIMMU''=//n//** An n-mode expansion of the $\mu$-tensor will be generated and transformed to polynomials up to 3rd order (default). The order can be changed by the integer passed to the ''NDIMMU'' keyword.
   * **''PSUM''=//n//** Maximum number of basis functions to be used within the fits of the surfaces (sum of exponents).   * **''PSUM''=//n//** Maximum number of basis functions to be used within the fits of the surfaces (sum of exponents).
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   * **''FITMETHOD''=//n//** (=1 Default) Within the iterative build-up of the individual subsurfaces, intermediate fitting will be used. This can be based on true multidimensional Kronecker product fitting (''FITMETHOD''=1) or on fitting along one-dimensional cuts (''FITMETHOD''=2).   * **''FITMETHOD''=//n//** (=1 Default) Within the iterative build-up of the individual subsurfaces, intermediate fitting will be used. This can be based on true multidimensional Kronecker product fitting (''FITMETHOD''=1) or on fitting along one-dimensional cuts (''FITMETHOD''=2).
   * **''FITxD''=//n//** The maximum order of the polynomials used for fitting within the iterative interpolation scheme can be controlled by the keywords ''%%FIT1D, FIT2D, FIT3D, FIT4D%%''. The default is given by 9. However in certain cases higher values may be necessary, but require an appropriate number of coarse grid points, which can be controlled by ''MIN1D'' etc. (See ''XSURF'' options) -->   * **''FITxD''=//n//** The maximum order of the polynomials used for fitting within the iterative interpolation scheme can be controlled by the keywords ''%%FIT1D, FIT2D, FIT3D, FIT4D%%''. The default is given by 9. However in certain cases higher values may be necessary, but require an appropriate number of coarse grid points, which can be controlled by ''MIN1D'' etc. (See ''XSURF'' options) -->
-  * **''ONLY''=//variable//** Sets one fit function for all coordinates. The possible fit functons are the same as for the option ''COORD''.+  * **''ONLY''=//variable//** Sets one fit function for all coordinates. The possible fit functions are the same as for the option ''COORD''. 
 + 
 +==== Scaling factors ==== 
 + 
 +''PSCAL'',//options// 
 + 
 +The 1D potential functions can be scaled by user-defined factors. This allows to fit potentials to experimentally determined frequencies. 
 + 
 +=== Options === 
 + 
 +  * **''MODE''=//n//** This is a mandatory information, which determines the mode to be scaled. 
 +  * **''SFAC''=//value//** Scaling factor to be used for the respective mode. 
 + 
 +The following example shows the scaling of the three modes of water. 
 + 
 +<code> 
 + {poly 
 +  pscal,mode=1,sfac=0.99924787 
 +  pscal,mode=2,sfac=0.99850975 
 +  pscal,mode=3,sfac=0.99900217} 
 +</code>
  
 <!-- <!--
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 ''PESTRANS'',//options// [pestrans] ''PESTRANS'',//options// [pestrans]
  
-The ''PESTRANS'' program allows to change the coordinate system being used within the representation of the potential by a Duschinsky-like transformation. This allows for the transformation of PESs as needed for the calculation of the vibrational spectra of isotopologues or Franck-Condon factors including Duschinsky rotations. This requires a representation of the potential energy surface by polynomials. Different versions of the ''PESTRANS'' program will be used in combination with the ''SURF'' and the ''XSURF'' programs. While for the old ''SURF'' program a fine grid in the new coordinate system will be generated from fits of the fine grid using the old coordinate system, the ''XSURF'' program itself will be used to generate a fine grid in the new coordinates, which usually is much faster. Due to that a completely different ''PESTRANS'' program will be used once ''XSURF'' has been called before. For further details see:\\+The ''PESTRANS'' program allows to change the coordinate system being used within the representation of the potential by a Duschinsky-like transformation. This allows for the transformation of PESs as needed for the calculation of the vibrational spectra of isotopologues or Franck-Condon factors including Duschinsky rotations. This requires a representation of the potential energy surface by polynomials. Different versions of the ''PESTRANS'' program will be used in combination with the ''XSURF'' program. For further details see:\\
  
 P. Meier, D. Oschetzki, R. Berger, G. Rauhut, //Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations//, J. Chem. Phys. **140**, 184111 (2014).\\ P. Meier, D. Oschetzki, R. Berger, G. Rauhut, //Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations//, J. Chem. Phys. **140**, 184111 (2014).\\
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 === Options === === Options ===
  
-  * **''CUT''=//n//** ''CUT=0'' (default) transforms all surfaces as requested by the input. ''CUT=1'' neglects the generation of vibrational-rotational coupling surfaces for the new potential. ''CUT=2'' neglects rotational-rotational coupling surfaces within the transformation and thus also for the new potential. +  * **''DVEC''=//n//** (=0 Default) This keyword controls the shift vector within the transformation. ''DVEC=0'' sets this vector to zero. 
-  * **''DVEC''=//n//** (=0 Default) This keyword controls the shift vector within the transformation. ''DVEC=0'' sets this vector to zero. This works only for ''XSURF'' calculations.+
   * **''ECKART''=//n//** By default the Eckart transformation matrix needed within the ''PESTRANS'' program will be computed explicitly. ''ECKART=0'' replaces the Eckart transformation matrix by a unit matrix.   * **''ECKART''=//n//** By default the Eckart transformation matrix needed within the ''PESTRANS'' program will be computed explicitly. ''ECKART=0'' replaces the Eckart transformation matrix by a unit matrix.
-  * **''NDIM''=//n//** Order of the $n$-mode potential for the transformed potential. The information of the original potential will be taken from the the ''POLY'' calculation. This option is only available for ''XSURF'' calculations. +  * **''NDIM''=//n//** Order of the $n$-mode potential for the transformed potential. The information of the original potential will be taken from the the ''POLY'' calculation. Note, the ''NDIMDIP'' keyword requests the intensity directive.  
-  * **''THRMATS''=//value//** Threshold controlling the analysis of the **S**-matrix indicating the accuracy of the transformation (default: ''THRMATS=0.3'').+  * **''THRSMAT''=//value//** Threshold controlling the analysis of the **S**-matrix indicating the accuracy of the transformation (default: ''THRSMAT=0.3'').
   * **''THRQ''=//value//** Elements in the displacement vectors below this threshold (default ''%%THRQ=10^{-8}%%'') will be neglected within the transformation.   * **''THRQ''=//value//** Elements in the displacement vectors below this threshold (default ''%%THRQ=10^{-8}%%'') will be neglected within the transformation.
   * **''TRANSTYPE''=//variable//** specifies the transformation to be performed by ''PESTRANS''. The default is generated automatically based on the given directives in the input stream.   * **''TRANSTYPE''=//variable//** specifies the transformation to be performed by ''PESTRANS''. The default is generated automatically based on the given directives in the input stream.
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-The following example shows a calculation for water including vibrational-rotational coupling surfaces, the corresponding VSCF and VCI calculations a subsequent transformation of the potential to doubly deuterated water.+The following example shows a standard calculation for water, the VSCF and VCI calculations after the call of the ''PESTRANS'' program refer a to doubly deuterated water.
  
 <code> <code>