renormalizations of the polarization sets done by MOLPRO on the MOLDEN input file

[Peter Knowles]

This bug has been recently fixed in the development version of
Molpro. After full verification, a patch will be provided for 2002.1
http://www.tc.bham.ac.uk/bugzilla/show_bug.cgi?id=216

At Sun, 17 Feb 2002 15:06:28 -0500,
Dave Moore wrote:
> 
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> Dear Sirs,
> 
> 	I am trying to use the MOLDEN files created by MOLPRO for
> visualization and manipulation of the molecular orbitals and
> densities.  I am checking my program by using the CUBE functionality
> of MOLPRO.  What I have found is that, as long as there are only s-
> and p-type orbitals in the basis set, my program gives precisely the
> same results as MOLPRO.  However, as soon as I add a polarization
> set, the results are different.  In trying to track down this
> discrepancy, I discovered (using orbprint) that the MO coefficients
> in the MOLDEN file are not the same as those in the MOLPRO file. 
> Since MOLDEN can only deal with cartesian (6D, 10F) polarization
> functions, I thought that specifying CARTESIAN in the MOLPRO input
> would fix this problem, but it doesn't ... the MO coefficients are
> still different between the MOLPRO output file and the MOLDEN file
> (the particulars are given below).
> 	Thus it seems that MOLPRO is expecting MOLDEN to use a different
> normalization condition for its polarization sets, but I cannot find
> documentation on it anywhere.  I would appreciate any details you can
> offer about the renormalizations of the polarization sets done by
> MOLPRO on the MOLDEN input file (for either the SPHERICAL or
> CARTESIAN cases, or both).  There does not seem to be any information
> about this in the MOLPRO manual or on the MOLDEN website.  Thank you
> in advance for your assistance.
> 
> Dave Moore
> Chemistry Dept.
> UNC Chapel Hill
> 
> 
> Specific discrepancies between MOLPRO and MOLDEN MO coeffients:
> 
> 1)  When using the CARTESIAN keyword in MOLPRO, it seems logical to
> me that the coefficients should not change at all between MOLPRO and
> MOLDEN, since MOLDEN also uses the cartesian (6D, 10F) polarization
> functions.  However this is not the case, MOLPRO divides the xx, yy
> and zz coefficients by sqrt(27.0) or 3**(1.5), before writing them to
> the MOLDEN file, while leaving the xy, xz and yz coefficients are
> unchanged.  I have tried to figure out the origin of this
> transformation without success (so far).  If both programs (MOLDEN
> and MOLPRO) are using normalized Gaussian primitives for their d-type
> basis functions, I do not understand how this can be correct.
> 
> 2)  When using CARTESIAN polarization functions, the f-orbitals
> coefficients are also changed between the MOLPRO and MOLDEN files. 
> Coefficients for primitives with an axis repeated 3 times (e.g. xxx),
> are divided by sqrt(3375.0) or 15**(1.5), and coefficients for
> primitives with an axis repeated twice are divided by sqrt(27.0)
> (same as for the d-orbitals).  Once again I do not understand the
> origin of this term, if normalized gaussian primitives are being used
> in both places.
> 
> 3)  When SPHERICAL polarization functions are used in MOLPRO, there
> are again some discrepancies between the coefficients in the MOLPRO
> and MOLDEN files.  Of course here there must be some transformation
> between the 5D representation used in MOLPRO and the 6D 
> representation used in MOLDEN, but I do not understand how it is
> determined.  I have not completely finished my analysis, but I have
> figured out the following correlations between the coefficients in
> the MOLPRO and MOLDEN files so far:
> 
> MOLPRO		MOLDEN
> d0	-->		dzz*sqrt(27.0)
> d1+   -->		dxz
> d1-	-->		dyz
> d2-	-->		dxy
> d2+	-->		a1*dxx + a2*dyy, 
> where a1 and a2 are coefficients I have not yet determined	
> 
> I do not understand these correlations, because the transforms I am
> used to are (for example):
> d1+ = a*dxz + a*dyz
> d1- = a*dxz - a*dyz
> where a is a normalization coefficient.
> but instead MOLPRO seems to be using d1+=dxz and d1-=dyz, which could
> certainly be correct, but is nonstandard (I think).  Finally, the
> factor of 3**(1.5) on the dzz coefficient is again confusing.
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--
Prof. Peter J. Knowles              
Email P.J.Knowles at bham.ac.uk  Phone +44-121-414-7472  Fax +44-121-414-7471
School of Chemical Sciences, University of Birmingham, Birmingham, B15 2TT, UK
WWW http://www.tc.bham.ac.uk/~peterk/