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--- pes_generators [2025/02/11 14:31] – rauhut
+++ pes_generators [2025/05/22 10:32] (current) – rauhut
@@ Line 65: / Line 65: @@
   * **''PSEUDOPOT''=//n//**. If the vibrational frequencies sould be computed with the Gmatrix formalism, $n$ determines the dimension of the expansion of the Wilson pseudopotential. Higher than 2 is not recommended-->
-The following example shows the input of a calculation which computes energy and dipole surfaces at the MP2/cc-pVTZ level and subsequently determines the anharmonic frequencies at the VSCF and VCI levels. Hartree-Fock calculations will not be restarted and the .log-file is directed to the scratch directory as defined by the $TMPDIR variable.
+The following example shows the input of a calculation which computes energy and dipole surfaces at the MP2/cc-pVTZ level and subsequently determines the anharmonic frequencies at the VSCF and VCI levels. Hartree-Fock calculations will not be restarted and the runtime option --logfile-scratch directs the .log-files to the scratch directory as defined by the $TMPDIR variable.
 <code>
@@ Line 106: / Line 106: @@
 ''INTENSITY'',//options//
-The ''INTENSITY'' directive of the ''XSURF'' program provides the option to alter the electronic structure methods for calculating the dipole surfaces. It also allows to define the VARDIP//n//D[X,Y,Z] variables separately. $n$ describes the dimension of the coupling surface and can be chosen to be 1 - 4.
+The ''INTENSITY'' directive of the ''XSURF'' program provides options for controlling the calculations of property surfaces as needed for the calculation of intensities. Currently, dipole surfaces (infrared intensities), polarizability tensor surfaces (Raman intensities) and quadrupole tensor surfaces are supported. The calculation of dipole surfaces can be combined with the calculation of polarizability or quadrupole surfaces, but the latter two exclude each other. Property surfaces can be computed for all those methods for which analytical expressions are available in Molpro. Considering dipole surfaces for the calculation of infrared intensities, for all methods except Hartree-Fock this requires the keyword ''%%CPHF,1%%'' after the keyword for the electronic structure method. In multi-level schemes for which the variables ''VAR1D'', ''VAR2D'' and ''VAR3D'' are set individually, the VARDIP//n//D[X,Y,Z] variables have to be set accordingly. The determination of dipole surfaces beyond Hartree-Fock quality effectively doubles the computation time for surface calculations.
-Dipole surfaces can be computed for all those methods for which analytical gradients are available in Molpro. For all methods except Hartree-Fock this requires the keyword ''%%CPHF,1%%'' after the keyword for the electronic structure method. In multi-level schemes for which the variables ''VAR1D'', ''VAR2D'' and ''VAR3D'' are set individually, the VARDIP//n//D[X,Y,Z] variables have to be set accordingly. The determination of dipole surfaces beyond Hartree-Fock quality effectively doubles the computation time for surface calculations.
 === Options ===
@@ Line 115: / Line 113: @@
   * **''NDIMDIP''=//n//** This denotes the term after which the $n$-body expansion of the dipole surfaces is truncated. The default is set to 3. Note that ''NDIMDIP'' has to be lower or equal to ''NDIM''.
   * **''NDIMPOL''=//n//** This variable denotes the term after which the $n$-body expansion of the polarizability tensor surfaces is truncated. The default is set to 0. Note that ''NDIMPOL'' has to be lower or equal to ''NDIM'' and must be smaller than 4. Note that currently only Hartree-Fock and MP2 polarizabilities are supported, which requires the ''POLARI'' keyword in the respective programs. Besides that, the frozen core approximation cannot yet be employed within the calculation of MP2 polarizabilities.
+  * **''NDIMQUAD''=//n//** This variable denotes the term after which the $n$-body expansion of the quadrupole tensor surfaces is truncated. The default is set to 0. Note that ''NDIMQUAD'' has to be lower or equal to ''NDIM'' and must be smaller than 4.
   * **''POLYSYM''=//variable//** (=ON Default). Symmetry in the polarizability surfaces differs from symmetry in energy or dipole surfaces and its recognition can be switched on or off. Symmetry is only detected based on geometrical parameters.
+  * **''QUADYSYM''=//variable//** (=ON Default). Symmetry in the quadrupole surfaces differs from symmetry in energy or dipole surfaces and its recognition can be switched on or off. Symmetry is only detected based on geometrical parameters.
   * **''VARDIPxDX''=//variable//** (x=1..4) Variable which is used for the $x$ direction of the dipole moment for 1D surfaces.
   * **''VARDIPxDY''=//variable//** (x=1..4) Variable which is used for the $y$ direction of the dipole moment for 1D surfaces.
@@ Line 137: / Line 137: @@
 {xsurf,info=1
- intensity,ndimpol=3
+ intensity,ndimpol=3 }
- scalnm,auto=on }
 poly,ndimpol=3
@@ Line 144: / Line 143: @@
 vci,pot=poly,version=4,ndimpol=3,info=1
 </code>
+A calculation for quadrupole intensities would require an input like
+<code>
+label1
+{hf
+ start,atden}
+{ccsd(t);expec,qm}
+{xsurf,info=1
+ intensity,ndimquad=3 }
+</code>
 ==== Restart capabilities ====
@@ Line 782: / Line 794: @@
   * always dump the potential energy surface to an external file.
+<!--
 ===== THE OLD PES GENERATOR (SURF) =====
@@ Line 788: / Line 800: @@
 The old ''SURF'' program for generating potential energy surfaces is still implemented, but is no longer supported. Several keywords are specific to the ''XSURF'' core and cannot be used together with ''SURF''. The new and much improved ''XSURF'' code follows the same philosophy and many options are the same as in the old ''SURF'' code, but ''XSURF'' cannot read any potential files being generated by ''SURF''. If you need to use the old ''SURF'' program, see older versions of the manual for the corresponding keywords.
+-->