From unipune.ernet.in!gadre@iucaa.ernet.in Wed May 1 03:50:06 1996 Received: from sangam.ncst.ernet.in for unipune.ernet.in!gadre@iucaa.ernet.in by www.ccl.net (8.7.1/950822.1) id DAA29589; Wed, 1 May 1996 03:27:27 -0400 (EDT) Received: from iucaa.UUCP (uucp@localhost) by sangam.ncst.ernet.in (8.6.12/8.6.6) with UUCP id NAA22393 for CHEMISTRY@www.ccl.net; Wed, 1 May 1996 13:00:12 +0530 Received: from unipune.ernet.in by iucaa (4.1/SMI-4.1) id AA11855; Wed, 1 May 96 11:54:51+050 Received: by unipune.ernet.in (5.0/SMI-SVR4.1.0) id AA01095; Wed, 1 May 1996 11:41:17 +0500 Date: Wed, 1 May 1996 11:41:17 +0500 From: gadre@unipune.ernet.in (Faculty) Message-Id: <9605011641.AA01095@unipune.ernet.in> To: CHEMISTRY@www.ccl.net Subject: BSSE Status: R Dear Sirs : WE are currently studying structures and energetics of weak intermolecular complexes. We have good starting geometries for A...B complexes wherein monomer geometries are kept intact. After full optimization(ab initio), however, the monomer geometries do change to some degree. For applying the Boys-Bernardi Counterpoise correction to monomer energies, which geometries should one choose? Thanks.......................................Shridhar Gadre gadre@unipune.ernet.in OR gadre@parcom.ernet.in --MAA27365.830849034/sangam.ncst.ernet.in-- From program@zinc.chem.ucalgary.ca Wed May 1 13:51:05 1996 Received: from zinc.chem.ucalgary.ca for program@zinc.chem.ucalgary.ca by www.ccl.net (8.7.1/950822.1) id MAA01956; Wed, 1 May 1996 12:07:29 -0400 (EDT) From: Received: by zinc.chem.ucalgary.ca (AIX 3.2/UCB 5.64/4.03) id AA05432; Wed, 1 May 1996 09:54:04 -0600 Message-Id: <9605011554.AA05432@zinc.chem.ucalgary.ca> Subject: Magnetic Susceptibility -- Summary To: CHEMISTRY@www.ccl.net Date: Wed, 1 May 1996 09:54:02 -0600 (MDT) Reply-To: schrecke@zinc.chem.ucalgary.ca X-Mailer: ELM [version 2.4 PL23] Content-Type: text <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< I sent this mail last week but it seems that it went wrong somehow. Therefore, I am trying again -- my apologies if you got this message more than once. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Dear netters, this is the summary to my recent question about computational methods to calculate magnetic susceptibilities. The collective wisdom of the net was again amazing, and I thank everybody who took the time to answer! This was my question: I am interested in calculations of the magnetic susceptibility, among other (static) magnetic properties. I know that the susceptibility is calculated in the IGLO program. I also know some references for this -- simply read about any IGLO paper. (good starting points are the various reviews of the IGLO method, e.g., W. Kutzelnigg et al, in: NMR Basic Principles and Progress, Vol.23, Springer-Verlag, Berlin, 1990, p. 165 W. Kutzelnigg et al, in: Nuclear Magnetic Shielding and Molecular Structure (W. Tossell, Ed.), NATO ASI Vol. C386, Kluwer, Dordrecht, 1993, p. 141 among others. The original references can be traced from the reviews) My question now is, are there other implementations of the susceptibility? I am curious about all kinds of methods, ab initio (like IGLO), DFT, semi-empirical ... ============================================================================== And here are the answers: ============================================================================== Steven Creve wrote Yes there are!! You should contact Denis R. Salahub: the calculation of all kinds of magnetic properties are implemented in his DFT-program: deMon. This program uses SOS-DFPT (=sum-over-states density functional perturbation theory) to calculate the second order properties in an IGLO manner. I would really appreciate it if you would send a summary of the answers to me or to the net, because I'm very interested in NMR & ESR parameters too. Thanks in advance Steven steven.creve@chem.kuleuven.ac.be ============================================================================== [Comment of G.S.:] I knew the work of Malkin / Salahub / Kaupp et al. myself but I hadn't come across anything about the susceptibility. Therefore, I doubt that the magnetic susceptibility is one of the many properties in deMon (cf. also the letter of Martin Kaupp below that doesn't mention anything like that) Maybe someone can update me with an appropriate literature reference about this point? ============================================================================== Doug Fox writes: Gaussian 94 can compute the susceptibility for the two multiple gauge methods implemented, CSGT and IGAIM, for both HF and DFT methods. Douglas J. Fox Director of Technical Support help@gaussian.com ============================================================================== Pascal Hebant writes: Hi, I am interested with the answers you will get Regards Pascal ***************************************************************************** Pascal HEBANT Laboratoire d'Electrochimie et de Chimie Analytique Ecole Nationale Superieure de Chimie de Paris 11 rue Pierre et Marie Curie 75005 Paris FRANCE tel: 33 (1) 44 27 66 94 fax: 33 (1) 44 27 67 50 http://alcyone.enscp.jussieu.fr/Pages/LECA/Electrochimie.html ***************************************************************************** ============================================================================== Kenneth Ruud writes: Hi! I can recommend our program DALTON (http://www.uio.no/~kenneth/hersiraba.html), which will give you magnetizabilities as the SCF and MCSCF level using London atomic orbitals (GIAOs). The SCF results using basis sets of DZP quality gives you results within 2% of the Hartree-Fock limit, which is significantly better than IGLO (which uses completeness relations in their derivations). We are not planning to distribute it freely before 1.January 1997, but if you are interested, we can probably provide you with something. Apart from that I guess you have the CADPAC program (DFT magnetizabilities with conventional orbitals), the program provided by Bader through the Gaussian94 code (I haven't seen calculations with small basis sets, so I don't know exactly how good it performs), but there exist a theory with supposedly better basis set convergence version in the SYSPRO(?) (can't quite recall) by Lazzeretti and coworkers. There is also the so called gauge invariant approach by Geertsen. Bishop and Cybulski has also the possibility of calculating MP2 magnetizabilities using conventional orbitals. If you are interested in any (or all) of these methods, please let me know, and I will provide you with proper references. Best regards, Kenneth _______________________________________________________________________________ Kenneth Ruud, Ph.d.-student in Chemical Physics at the Department of Chemistry, University of Oslo, Norway. E-mail: kenneth@dalton.uio.no I don't know what the computer language of the year 2000 will look like, but I know it will be called FORTRAN. _______________________________________________________________________________ ============================================================================== [Comment from G.S.] I asked them for the references so that I could add them to the summary. Here they are: ============================================================================== Hi, Georg! I hope you don't mind BiBTeX style, as it is the easiest for me. References to our own work with GIAOs: AUTHOR = {K.Ruud and T.Helgaker and K.L.Bak and P.J{\o}rgensen and H.J.Aa.Jensen}, KEY = {Hartree-Fock limit magnetizabilities from London orbitals}, JOURNAL = {J.Chem.Phys.} , VOLUME = 99 , YEAR = 1993 , PAGES = 3847 } AUTHOR = {K.Ruud and T.Helgaker and K.L.Bak and P.J{\o}rgensen and J.Olsen}, KEY = {Accurate magnetizabilities of the isoelectronic series BeH$^{-}$, BH and CH$^{+}$. The MCSCF-GIAO approach}, JOURNAL = {Chem.Phys.} , VOLUME = 195 , YEAR = 1995 , PAGES = 157 } A nice application showing the strength of GIAOs is: AUTHOR = {K.Ruud and H.Skaane and T.Helgaker and K.L.Bak and P.J{\o}rgensen}, KEY = {Magnetizability of hydrocarbons}, JOURNAL = {J.Am.Chem.Soc.} , VOLUME = 116 , YEAR = 1994 , PAGES = 10135 } We are also soon (K.V.Mikkelsen, K.Ruud and T.Helgaker, Chem.Phys.Lett. 253, p.443 (1996) (May 10 volume)) presenting an application where GIAOs have been combined with the dielectric continuum model. Baders work: AUTHOR = {T.A.Keith and R.F.W.Bader}, KEY = {Calculation of magnetic response properties using a continous set of gauge transformations}, JOURNAL = {Chem.Phys.Lett.} , VOLUME = 210 , YEAR = 1993 , PAGES = 223 } Lazzerettis work: AUTHOR = {S.Coriani and P.Lazzaretti and M.Malagoli and R.Zanasi}, KEY = {On CHF calculations of second-order magnetic properties using the method of continuous transformations of origin of the current density}, JOURNAL = {Theor.Chim.Acta} , YEAR = 1994 , VOLUME = 89 , PAGES = 181 } AUTHOR = {P.Lazzaretti and M.Malagoli and R.Zanasi}, KEY = {Computational approach to molecular magnetic properties by continuous transformation of the origin of the current density}, JOURNAL = {Chem.Phys.Lett.} , VOLUME = 220 , YEAR = 1994 , PAGES = 299 } AUTHOR = {R.Zanasi and P.Lazzaretti and M.Malagoli and F.Piccinini}, KEY = {Molecular magnetic properties within continuous transformations of origin of the current density}, JOURNAL = {J.Chem.Phys.} , VOLUME = 102 , YEAR = 1995 , PAGES = 7150 } Geertsens work: AUTHOR = {J.Geertsen}, KEY = {Origin-independent polarization propagator calculations of magnetizabilities}, JOURNAL = {Chem.Phys.Lett.} , VOLUME = {188}, YEAR = {1992}, PAGES = {326} } Handys work: AUTHOR = {S.M.Colwell and N.C.Handy}, KEY = {The determination of magnetisabilities using density functional theory}, JOURNAL = {Chem.Phys.Lett.} , VOLUME = 217 , YEAR = 1994 , PAGES = 271 } But also look at: AUTHOR = {A.M.Lee and N.C.Handy and S.M.Colwell}, KEY = {The density functional calculation of nuclear shielding constants using London atomic orbitals}, JOURNAL = {J.Chem.Phys.} , VOLUME = 103 , YEAR = 1995 , PAGES = 10095 } In addition there are several other references to applications, and to papers about choices of a common gauge origin. ============================================================================== Martin Kaupp writes: [a few lines deleted] As far as I know, the Oslo group (e.g. K. Ruud) uses SCF- and MCSCF-GIAO extensively for susceptibilities as well. The same holds, I think, for Oddershede et al. within the LORG and SOPPA approaches. Experience of Handy and coworkers with DFT (CDFT-GIAO) are discouraging (unlike what is known for chemical shieldings), probably as the susceptibility probes the long-range behavior of the V_xc functionals. The reference is: A.M.Lee,S.M.Colwell,N.C.Handy Chem.Phys.Lett.1994,229,225. Cf. their paper on CDFT for shieldings: J.Chem.Phys. 1995,103,10095. Gruss, Martin ------------------------------------------------------------------ | Dr. Martin Kaupp | | Max-Planck-Institut fuer Festkoerperforschung, | | Heisenbergstrasse 1, D-70569 Stuttgart, Germany, | | Tel.: country-code+711/689-1532 | | Fax.: country-code+711/689-1562 | | email: kaupp@vsibm1.mpi-stuttgart.mpg.de | | | | and Institut fuer Theoretische Chemie, Universitaet Stuttgart, | | Pfaffenwaldring 55, D-70569 Stuttgart, Germany | | Tel.: country-code+711/685-4399 | | Fax.: country-code+711/685-4442 | | http://www.theochem.uni-stuttgart.de/~kaupp/ | ------------------------------------------------------------------ ============================================================================== <<<<<<<< END OF SUMMARY >>>>>>>>> ============================================================================== Georg Schreckenbach Tel: (Canada)-403-220 8204 Department of Chemistry FAX: (Canada)-403-289 9488 University of Calgary Email: schrecke@zinc.chem.ucalgary.ca 2500 University Drive N.W., Calgary, Alberta, Canada, T2N 1N4 ============================================================================== From rino@ibc.wustl.edu Wed May 1 13:51:15 1996 Received: from wugate.wustl.edu for rino@ibc.wustl.edu by www.ccl.net (8.7.1/950822.1) id LAA01925; Wed, 1 May 1996 11:58:35 -0400 (EDT) Received: from ibc.wustl.edu by wugate.wustl.edu (8.6.12/8.6.11) with ESMTP id KAA20730 for ; Wed, 1 May 1996 10:58:34 -0500 Received: by ibc.wustl.edu (SMI-8.6/SMI-SVR4) id KAA23535; Wed, 1 May 1996 10:58:32 -0500 Date: Wed, 1 May 1996 10:58:31 -0500 (CDT) From: Rino Ragno To: Computational Chemistry List Subject: MOZYME- summary In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Some days ago I did the following question: > > > Dear netters, > > I have read about a program called MOZYME, by James J. P. Stewart and I > would like to try it. > > Any of you out there does know anything about it? > > Thank you > > Rino > > ++---------------------------------------------------------------------------++ > ++---------------------------------------------------------------------------++ > || || > || Dr. Rino Ragno E-mail: rino@wucmd.wustl.edu || > || Institute for Biomedical Computing or: rino@ibc.wustl.edu || > || Center for Molecular Design Phone : 314-362-2273 || > || Box 8036, Washington University FAX : 314-362-0234 || > || 700 South Euclid Avenue || > || St. Louis, Missouri 63110 || > || U. S. A. || > || || > ++---------------------------------------------------------------------------++ > ++---------------------------------------------------------------------------++ Here are the answers: From Edward C. Hauer Rino, here's what I found using an Altavista search for MOZYME: DONORS TO MOPAC 93 Project MOPAC | About | This page | MOZYME | Back to Home Page | DONORS TO MOPAC 93. New http://iti2.net/jstewart/tom.htm - size 6K - 20 Apr 96 http://iti2.net/jstewart/pdb.htm - size 11K - 20 Apr 96 Description of MOZYME, Version 1 Project MOPAC: MOZYME | About | This page | MOPAC 93 | Back to Home Page | Web-Page: HTTP://ITI2.NET/JSTEWART/ Tel: USA+(719) 488-9416 FAX: USA+(719)... http://iti2.net/jstewart/mozdesc.htm - size 14K - 20 Apr 96 Description of MOPAC 93 Project MOPAC | About | This page | MOZYME | Back to Home Page | Web-Page: HTTP://ITI2.NET/JSTEWART/ Tel: USA+(719) 488-9416 FAX: USA+(719) Project MOPAC - Other Interesting Sites Project MOPAC - Other Interesting Sites | About | MOPAC 93 | MOZYME | This page | Back to Home Page. Other Interesting Sites. Cambridge Soft has added... http://iti2.net/jstewart/related.htm - size 2K - 21 Apr 96 Project MOPAC - Jimmy Stewart Project MOPAC Jimmy Stewart | About | MOPAC 93 | MOZYME | Back to Home Page | Project MOPAC - Jimmy Stewart. Address: Dr James J. P. Stewart, Stewart... http://iti2.net/jstewart/jstewart.htm - size 839 bytes - 21 Apr 96 Project MOPAC - Fujitsu Project MOPAC - Information on Fujitsu | About | Home| MOPAC 93 | MOZYME | This page | Back to Home Page. FUJITSU. Inquiries concerning MOPAC 93 and... http://iti2.net/jstewart/fujitsu.htm - size 1K - 21 Apr 96 Project MOPAC Project MOPAC Home Page | About | MOPAC 93 | MOZYME | This page | Web-Page: HTTP://ITI2.NET/JSTEWART/ Tel: USA+(719) 488-9416 FAX: USA+(719) 488-9758.... http://iti2.net/jstewart/default.htm - size 8K - 20 Apr 96 Project MOPAC Project MOPAC Home Page | About | MOPAC 93 | MOZYME | This page | Web-Page: HTTP://ITI2.NET/JSTEWART/ Tel: USA+(719) 488-9416 FAX: USA+(719) 488-9758.... http://iti2.net/jstewart/ - size 8K - 19 Apr 96 Description of MAKPOL Project MOPAC: MAKPOL | About | This page | MOPAC 93 | Back to Home Page | Web-Page: HTTP://ITI2.NET/JSTEWART/ Tel: USA+(719) 488-9416 FAX: USA+(719)... http://iti2.net/jstewart/makdesc.htm - size 5K - 21 Apr 96 Omer Casher and Henry Rzepa: Poster Omer Casher and Henry Rzepa. Chemical Collaboratories using the Internet. The Explorer EyeChem suite is a set of modules suitable for molecular... http://www.gene.cinvestav.mx/talks/mgs/poster.html - size 1K - 5 Apr 95 Results and discussion 2. RESULTS AND DISCUSSION. The model reaction between alpha-halopenicillins and a methoxide anion (serine analogue) was studied at the PM3 or AM1 levels.... http://www.ch.ic.ac.uk/local/projects/s-smith/project/results.html - size 52K - 15 Jun 95 No Title 1. F. H. Allen, J. E. Daview, J. J. Galloy, O. Johnson, O. Kennard, C. F. Macrae, E. M. Mitchell, G. F. Mitchell, J. M. Smith and D. G. Watson, J. Chem.... http://chem.leeds.ac.uk/papers/html/Perkin2/hyperactive_molecules_fn.html - size 3K - 17 Apr 96 Casher, Chandramohan, Hargreaves, Leach, Murray-Rust, Sayle, Rzepa, Whitaker Hyperactive Molecules and the World-Wide-Web Information System. Omer Casher,a. Gudge K. Chandramohan,b. Martin J. Hargreaves,b. Christopher J. Leach,a.... http://chem.leeds.ac.uk/papers/html/Perkin2/tartrazine.html - size Description of MOZYME History Current Status Definition 93 Capabilities Definition Examples of Data Limitations Dynamic Memory Bugs fixed Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed History of MOZYME The idea behind MOZYME was conceived on a fishing boat on the way back from the Gothenberg Archepeligo during a conference at Aspenas. Prof. Allinger had given some very enjoyable talks on molecular mechanics, and it was singularly frustrating to be aware that we could never hope to run such large systems using conventional matrix algebra. Near the end of an afternoon excursion, during which there was a little too much to drink, the idea of using Lewis structures as an alternative to matrix algebra was born. Of course, the idea itself was not novel, but perhaps the way in which the idea was rendered as method and then as FORTRAN code is novel. Anyhow, from the start of method development, in May 1993, until now, May 1996, the project has matured into the program MOZYME. The first stage was to do a feasibility study - that took about one entire year! After that came the extension of the original concept so that it would work for a wide range of systems, and to include the dull but essential features such as restarts, data-checking routines, and output routines. Finally, the method was published, and many test cases were run, and a distribution tape made, so that researchers could reproduce the calculations described in the publications. Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Current Status of MOZYME MOZYME is copyrighted software. Fujitsu is the copyright owner. Researchers interested in getting a copy of MOZYME should contact Fujitsu. No version of MOZYME will be placed in the public domain for the forseeable future. MOZYME has a limited range of functionalities. Among these are: 1. Electronic Structure Calculations Restricted Hartree Fock for closed-shell systems. 2. States Ground State 3. Symmetry None 4. Geometric Functions BFGS Geometry Optimizer. Baker's Eigenfollowing Geometry Optimizer Transition State Location for Reactions. Reaction Coordinate Following. Symmetry constraints Ability to specify parameters to be optimized. 5. Other Capabilities Solid state (polymers, layers, and solids) Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Definition of MOZYME MOZYME is a semiempirical quantum chemical program for the study of large systems. The methods in MOZYME are similar to those in MOPAC. The fundamental difference is that, whereas MOPAC uses matrix algebra for the solution of the self-consistent field equations, MOZYME uses localized molecular orbitals. Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Examples of MOZYME calculations Examples of systems that have been run successfully using MOZYME are Grignard reagent Methyl magnesium bromide can be drawn as a Lewis structure as Me(-) Mg(++) Br(-) Benzaldehyde Using localized orbitals, delocalized systems can be modeled. Crambin The geometry of a small cross-linked protein is optimized. Poly paraphenylenebenzobisthiazole A highly delocalized one-dimensional polymer. Boron Nitride A simple two-dimensional layer system. DiamondA simple three-dimensional solid A Protein from the Brookhaven Protein Data Bank Rhizomucor miehei Lipase A large protein. Examples of Data Grignard Reagent A single-point calculation of Methyl Magnesium Bromide demonstrates that quite complicated Lewis structures can readily be handled. Examples of Data Benzaldehyde Examination of the 3 dimensional structure of benzaldehyde shows the following Lewis structural elements: 6 C-H single bonds. 6 C-C sigma bonds in the aromatic ring. 1 C-C sigma bond to the carbon of the aldehyde group. 1 C-O sigma bond. 3 C=C pi-bonds in the aromatic ring. 1 C=O pi bond. 2 lone pairs on the oxygen. There are thus 18 bonds and 2 lone pairs - these form the occupied set of localized molecular orbitals. For every bond there is an antibond, therefore there are 18 antibonds. These form the virtual set of LMOs. The results of a MOZYME run show that the electronic structure is the same as that from MOPAC. In both these calculations, the starting points were the same. For this calculation, MOZYME took about 70 seconds to MOPAC's 13 seconds. Much of the extra time can be accounted for because MOZYME geometry optimizer is less efficient... Examples of Data Crambin Crambin is a 46 residue protein found in Abbysinian cabbage seed. From the PDB file the 3 dimensional structure shows that crambin is highly compact. A 1SCF calculation shows that 7 residues are ionized. The heat of formation of the optimized geometry is -XXXX kcal/mol. Examples of Data Poly-paraphenylenebenzobisthiazole Like MOPAC, MOZYME can model high polymers with large unit cells. Thus PBT, a system with a three ringed heterocyclic fragment and one para-phenyl ring per unit cell is best represented in the calculation by three fundamental unit cells. The elastic modulus of such a system can be calculated using Hook's law - stretch the unit cell, and monitor how the heat of formation changes. Examples of Data Boron Nitride Boron nitride illustrates a two-dimensional layer system. For this calculation, 49 fundamental unit cells were used as the unit cell. In the calculation, each unit cell is surrounded by 8 = (3**N)-1 other unit cells, where N is the dimensionality of the system. After geometry optimization, a 1SCF calculation gives the final electronic structure. Examples of Data Diamond Like MOPAC, MOZYME can calculate the electronic structure of three-dimensional systems. A good test case is diamond: every atom is in the same environment and any differences in the electronic structure of the atoms is an indication of errors in the method. Using a cluster of 216 atoms, the results of a 1SCF calculation show that all the atoms are, indeed, identical. Making the unit cell bigger, to 512 atoms, did not result in any significant change in the electronic structure. Examples of Data Rhizomucor miehei Lipase This system has 4,054 atoms. As with crambin, the 3 dimensional structure shows that the protein is highly compact. A 1SCF calculation shows that 7 residues are ionized. Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Limits of MOZYME Inadequate testing Because it is completely new, MOZYME has not been tested in independent laboratories, it has only been tested in the laboratory where it was developed. Of course, within a year, this limitation should be corrected. No UHF or open shell systems The only systems that can be run are those for which a Lewis structure can be written. Systems allowed include: Conventional molecules benzene, water, proteins, some ions, such as C2H5(-) and NH4(+), polymers, layer systems, and solids. Multiple Species Systems of two or more moieties, such as proteins with many water molecules; proteins composed of two or more non-covalently joined chains; ionic systems, such as methyl magnesium bromide (in which the magnesium is not bonded to anything, but has a +2 charge); and systems where the various moities are well separated, such as CH4 and a distant CH3(+). Transition states Only those transition states for which Lewis structures can be drawn are allowed. Thus the TS for CH4 + CH3(+) = CH3(+) + CH4 is allowed, because it can be written with the central hydrogen bonded to one carbon, and the charge put on the other carbon. Even though the TS is symmetric, the ONLY requirement is that the system can be drawn using Lewis structural elements. Hypervalent systems Only systems that can be written with Lewis structures are allowed. Thus the following hypervalent species can be modeled: H2SO4, H3PO4, PO4(3-), Adenosine triphosphate, BF3:NH3, SO2. Systems that cannot be modeled include: Radicals Examples: Methyl (CH3.), ethyl (C2H5.), NO2, and the ground state of O2. All these systems have open shell ground states. Electronic Excited States Closed shell O2, twisted (D2d) ethylene, square cyclobutane. Reactions involving open shells (Suggestions?) Other limitations 1. No eigenvectors 2. No symmetry recognition 3. No solvation models 4. No electrostatic potentials 5. No vibrational phenomena Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Memory Requirements of MOZYME MOZYME uses dynamic memory allocation. A few one-dimensional arrays are 'hard wired' in, but all the big arrays are assigned at run time. As distributed, MOZYME is configured to run systems of up to 10,000 atoms. If a very small system is run, then the size of the running executable is a little less than 2.5 megabytes. The extra memory required for larger systems is proportional to the square of the size. This is a result of the electrostatics, which involve every pair of atoms. The largest system run during the testing phase was just over 4,000 atoms, and that ran in about 400 megabytes. Top | History | Current Status | Definition | Examples of Data | Limitations | Dynamic Memory | Bugs fixed Bugs Corrected As MOZYME is completely new, no bugs are known at the present time. (1-May-1996) c 1996 James J. P. Stewart Comments to jstewart@fai.com URL:http://iti2.net/jstewart Thanks a lot to Ed Rino