RE: Re: Physical Constants package

*To*: mathgroup at smc.vnet.net*Subject*: [mg46969] RE: [mg46954] Re: Physical Constants package*From*: "David Park" <djmp at earthlink.net>*Date*: Thu, 18 Mar 2004 01:24:54 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Curt, You may wish to try out the V4ExtendUnits and V4ReducedUnits package at my web site below. It allows you to install your own units, such as Hartree, and it allows you to setup reduced unit systems where certain physical constants are equal to 1 and then freely convert from and to standard units. But on your second question: all you have to do is to Convert to 1. 0.39789711297139907/(Meter^3*(Kilogram/(Joule*Second^2))^(3/2)); Convert[%, 1] 0.397897 Needs["Miscellaneous`V4ExtendUnits`"] Needs["Miscellaneous`V4ReducedUnits`"] Needs["Miscellaneous`PhysicalConstants`"] 0.39789711297139907/(Meter^3*(Kilogram/(Joule*Second^2))^(3/2)) // ToUnit[1] 0.397897 To install and use Hartree as a unit... InstallNewUnit[Hartree -> 27.211 ElectronVolt] 50 Erg // ToUnit[Hartree] 1.14687*^12*Hartree 20Hartree // ToUnit[Rydberg] 39.9989 Rydberg To install atomic units... e = ElectronCharge; me = ElectronMass; a0 = BohrRadius; \[HBar] = PlanckConstantReduced; SetupReducedUnits[{\[HBar], a0, me, e}, {Kelvin}] {Ampere -> 150.97490094886209, Kilogram -> 1.0977693252662292*^30, Meter -> 1.889726133921251*^10, Second -> 4.134137333612569*^16} SpeedOfLight // ReducedUnits 137.036 En == (1/2)*(\[HBar]^2/(me*a0^2))*(Z^2/n^2)//ReducedUnits En == 0.5*Z^2/n^2 50Erg // ReducedUnits ReducedEquivalent[%, 1, Meter] 1.146856*^12 60.689 Meter David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Curt Fischer [mailto:crf3 at po.cwru.edu] To: mathgroup at smc.vnet.net On a sort-of related note, does anyone know when quantum chemistry units (energy in Hartrees, distance is Bohrs, etc) will find there way into the Miscellaneous`Units` package? Also, is there any good way to get Mathematica to simplify expressions such as 0.39789711297139907/(Meter^3*(Kilogram/(Joule*Second^2))^(3/2))? Plain inspection shows that the units all cancel out, but the Miscellaneous`Units` package doesn't do the job. In general, the problem seems to be with units to some non-integer power. -- Curt Fischer