Subject: NWChem: various questions, problems

From: Brian Barnes <[email-masked]>
Date: Mon, 10 Feb 2003 17:06:42 -0600

Hello all.  This is my first posting to the list, although I have browsed
it on the web off an on over the past couple years.  Recently, our
research group has been using NWChem to examine some small water clusters.
( http://www.emsl.pnl.gov:2080/docs/nwchem/nwchem.html )

While overall a good program, especially when paired with their job
creation/manager program, Ecce, we have run into a few snags.  All of
these have been submitted through the offical reporting channels (and a
few have been solved, and patch provided by NWChem dev team) and I'd
like to see if anyone on CCL has a solution to these problems that we
haven't resolved yet.

I'll be as brief as possible .. more verbose input files or error messages
are available upon request.  All calculations have been attempted on an
AMD/linux cluster and a SGI Origin2000.

Problem 1:  B3LYP/aug-cc-pVTZ frequency calculation on S4 symmetry cyclic
water tetramer crashes.  Calculation does not crash when aug-cc-pVDZ basis
set is used.  Freq calcs on some different systems using aug-cc-pVTZ have
been successful.  Geometry used for input is:

geometry autosym units angstrom
 O     1.37380     1.37380     0.00536900
 O     -1.37380     1.37380     -0.00536900
 O     1.37380     -1.37380     -0.00536900
 O     -1.37380     -1.37380     0.00536900
 H     1.51067     0.398269     -0.00383100
 H     -0.398269     1.51067     0.00383100
 H     0.398269     -1.51067     0.00383100
 H     -1.51067     -0.398269     -0.00383100
 H     1.87950     1.68938     0.764311
 H     -1.68938     1.87950     -0.764311
 H     1.68938     -1.87950     -0.764311
 H     -1.87950     -1.68938     0.764311
end

part of error from the SGI, after 'Multipole Analysis' section of output:

 Read molecular orbitals from ./tetramer.movecs

                     2 grinfo reading failed                    2
  calling routine: intdd_1eh1
 int_c2s_mv: lscr to small by      1665
2:2:int_c2s_mv: lscr to small by:: 1665
2:2:int_c2s_mv: lscr to small by:: 1665
Last System Error Message from Task 2:: Result too large
  2: ARMCI aborting 1665 (0x681).

---

Problem 2: In the above mentioned water tetramer (to use one example): the
automatic detection of symmetry in the output is C2.  However, the symmetry
toolkit in Ecce's builder correctly identifies the more exact S4 point
group.  I do not know if this is a bug, or just a lack of feature.
Certainly the calculation would go faster if S4 symmetry could be
exploited instead of C2.  I might get around to building it as a S4
cluster using symmetry-specific input to see what happens.

---

Problem 3:  this is a 'lack of feature' that I'm curious if anyone has a
patch to fix..

Dipole Moment Analysis is not available in NBO.  As noted from a NBO 5.0
webpage at http://www.chem.wisc.edu/~nbo5/EX_DIPOL.HTM , "The DIPOLE
keyword requires that the host program provide dipole integrals, and is
hence unavailable for some packages."  Although the dipole keyword is
recognized, as shown in the output as:

       /DIPOLE / : Print NBO/NLMO dipole moment analysis

...no such dipole information is present in the output.

---

Problem 4: this one is a bit harder to explain, so I'm including more
information.  method was B3LYP/aug-cc-pVDZ.  this is also new; we're just
sending it off to the NWChem people today.

When using ghost atoms with orbitals to perform a BSSE (basis
set superposition error) calculation, and geometry input is read-in as
z-matrix, DFT sometimes fails to provide a reasonable energy.  NOTE: this
is using nwchem 4.1 (there was a known problem, now fixed, with ghost
orbitals + DFT in previous versions). Furthermore, the cartesian
coordinates generated by the z-matrix input do not match those generated
by babel for the same z-matrix (there is an inversion of signs in the x
and z coordinates).  However, MP2 gives equivalent, "correct",  results
for both z-matrix and all cartesian coordinate inputs.

I have performed the following calculations:

1. DFT + z-matrix (the input type our work requires)
2. DFT + cartesian coords (generated by babel, from z-matrix in #1)
3. DFT + cartesian coords (coordinates taken from nwchem output in #1)
4. MP2 + z-matrix
5. MP2 + cartesian coords (generated by babel, from z-matrix in #1)

#1 and #3 produce unreasonable energies with the following error during
the energy calculation at every iteration:

 WARNING: error on integrated density =  0.20E+02
 greater than required accuracy of  0.10E-06

attempts to remove this error by turning off DIIS, raising tolerance for
initial guess, or changing DFT integration grid density have failed.

input z-matrix and basis for "#1" follows:

geometry autosym units angstrom
            zmatrix
                H
                O    1 r2
                H    2 r3    1 a3
                X2    3 r4    2 a4    1 d4
                X1    4 r5    3 a5    2 d5
                X1    4 r6    3 a6    2 d6
                variables
                r2 0.9637
                r3 0.8728
                a3  95.07
                r4 1.8441
                a4 172.11
                d4 179.97
                r5 0.9654
                a5 110.73
                d5  58.09
                r6 0.9654
                a6 110.73
                d6 301.91
            end
end

basis "ao basis" spherical print
  H library "aug-cc-pVDZ"
  O library "aug-cc-pVDZ"
  X1 library H aug-cc-pVDZ
  X2 library O aug-cc-pVDZ
END