From ng436@traken.pnl.gov Fri Feb 26 13:34:24 1993 Date: Fri, 26 Feb 1993 21:34:24 -0800 From: ng436@traken.pnl.gov (Dave E Woon) Message-Id: <9302270534.AA09760@traken.pnl.gov> To: chemistry@ccl.net, ole.swang@kjemi.uio.no Subject: Re: language question >From "Amo, Amas, Amat and More (How to Use Latin to Your Own Advantage ET AL. abbreviation of "et alii," "et aliae," "et alia" This abbreviation is used in writing to avoid a lengthy listing. "Et alii" (et AH-lee-ee) is masculine, so it is properly used in speech to mean "and other men" when preceded by the name of a male or to mean "and other people." "Et aliae: (AH-lee-i) is feminine, so it is properly used in speech to mean "and other women." "Et alia" (AH-lee-ah) is neuter, so it is properly used in speech to mean "and other things." Educated people do not pronounce the abbreviation et al. "And others" is said for et al. ==== As you say, it doesn't relate much to computational chemistry, so I'm responding to you via email only. However, one of my pet peeves regards the pronuciation of "ab initio," another bit of Latin which is also discussed in the book "Amo, Amas, Amat and More." Some people say "ab" to rhyme with the American "cab", others use "ahb" to rhyme with "cob," but "initio" is invariably pronounce "ih-NIHSH-ee-oh." To use "ahb" is more correct Latin, but then NIHSH is wrong: according to the book, it's "ih-NIH-tee-oh." No "SH" at all... David Woon Molecular Science Research Center Battelle Pacific Northwest Labs Richland, Washington From UDIM018@FRORS31.bitnet Sat Feb 27 10:02:12 1993 Message-Id: <199302271329.AA23713@oscsunb.ccl.net> Date: 27 Feb 93 14:02:12 EDT From: Subject: semiempircal calculations simple oxides To: chemistry@ccl.net E. M. EVLETH Dynamique des Interactions Moleculaires Universite Pierre et Marie Curie 4 Place Jussieu, Tour 22, Paris 75005 33-1-44-27-42-08 (work), 33 = France; 1 = Paris 33-1-45-48-67-20 (home) FAX 33-1-44-27-42-17 e-mail UDIM018 at FRORS31 The semiemprical parameterizations developed by Dewar's group never have produced 'good' results on nitrogen and chlorine oxides, peroxides etc. and PM3 is no better. STD heats of formation errors are in the 20 kcal region, structures sometimes bizare. Even molecular triplet oxygen, which should be zero is 20 kcals off (AM1, MINDO3 is better). You'll have better 'luck' sticking to large polyatomics, and organics by preference. Unfortunately nobody has published a list of 'dos and don'ts' in semiempirical methods, a poor calculation can serve as a good example. But those committed to semiempirical methodes prefer an upbeat approach and speak no evil. Ab initioists dont care about semiemprical screwups but have their lists of pathological structures (NO3 radical, ClOO, FOOF etc) too, but can work hard to getting them right. And you have to be a relatively attentive doctor to know when your structure is sick. NO2 and NO monomers and dimers are strange beasts. Beware