Maxwell: multipole expansion for condensed phases 

Last updated: 11/15/04 
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The Maxwell package implements the Maxwellian formalism for calculating the interaction energy between charge distributions as represented by the multipole expansion. For crystals, the program implements E. Campbell's formulation of Ewald summation for multipoles of arbitrary order. Other algorithms used in the programs were developed by M. Mezei and E. Campbell.
The Maxwellian formalism extracts scalar multipoles p^{N} and unit vectors (called characteristic directions) s^{N} from the Cartesian moments M(L,M,N,O) from the respective charge distributions and calculates the multipole expansion around a center O of the electrostatic energy of two charge distributions as directional derivatives:
The suite of programs in Maxwell includes calculation of the Cartesian multipoles {M(L,M,N,O)} from a singledeterminant wave function, optionally partitioning the electron density; calculation of the socalled poles and characteristic directions ({p^{N}}, {s^{N}}) used in the Maxwellian formalism; calculation of interaction energy among a finite set of charge distributions; calculation of interaction energy of an inifinite lattice of multipoles.
See the full documentation for more detail and for references. Some of the papers can be dowloaded from the table below.
The role of the individual programs of the package is summarized below:
Program  Input  Output  MS Copy 

MOMENTS  Wave function  {M(L,M,N,O)} 
Density partitioning, integrals, contracting and transforming moments 
MOMTRNSF  {M(L,M,N,O)}  {M(L,M,N,O')}  
CHARDIR  {M(L,M,N,O)}  {p^{N}}, {s^{N}}  
MULTIPOL  {p^{N}}, {s^{N}}, {x_{i}i=1,n}  E(1,2,...,n,N_{max})  Permanent multipole: Induced multipole: 
CRYSCON  {x_{i}i=1,n}, {p^{N}}, {s^{N}}  "Crystal constants" 
Theoretical foundations Detailed formalism 
CRYSTEN  "Crystal constants", molecular orientations  E(crystal,N_{max})  
CRYSPOT  {x_{i}i=1,n}, molecular orientations  E(crystal,nonelectrostatic) 