	/** 3-particle P-state laplacian in interparticle coordinates **/

/*K: laplacian */
/*A: John Gottschalk */
/*S: Universtiy of Western Australia	*/
/*D: March 1987 */
/*P: Four files, XLaplacianS, XSymbols, XLapdata and XDerivdata, are loaded. 
	The last three are to be created by the user to taylor this file 
	(XLaplacianP) to his/her needs. XSymbols should contain a list of any 
	user-defined symbols written in terms of interparticle coordinates. 
	XLapdata should contain extra definitions for the Laplacian operator, 
	for example Lap[Log[r12 (2r^2-r12^2)^(1/2)-r1^2+r2^2]] : 0.
	XDerivdata should contain extra definitions needed for D[$$x] and 
	Dt[$$x]. In addition symbols which are constant with respect to 
	differentiation should be included in this file. */


Loadonce[XLaplacianS]
Loadonce[XDerivdata]
Loadonce[XSymbols]
Loadonce[XLapdata]

/*: NLapP[$expr]
	produces the action of the P-state Laplacian to $expr. */
	
NLapP_:Op_:Tier
NLapP[$e] :: LapS[$e] + Op[$e]


Op[$e] :: 2 Dt[$e,r1]/r1 +\
          2 Dt[$e,r2]/r2 + \
	  4 Dt[$e,r12]/r12

Cos[theta]  : (r1^2+r2^2-r12^2)/(2r1 r2 )
Cos[theta1] : (r1^2+r12^2-r2^2)/(2r1 r12)
Cos[theta2] : (r2^2+r12^2-r1^2)/(2r2 r12)

