/*
    DFT++ is a density functional package developed by the research group
    of Professor Tomas Arias

    Copyright 1996-2003 Sohrab Ismail-Beigi

    This file is part of DFT++.

    DFT++ is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    DFT++ is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with DFT++; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Please see the file CREDITS for a list of authors.

    For academic users, we request that publications using results obtained with
    this software reference

    "New algebraic formulation of density functional calculation," by Sohrab Ismail-Beigi
    and T.A. Arias, Computer Physics Communications 128:1-2, 1-45 (June 2000).

    and, if using the wavelet basis, further reference

    "Multiresolution analysis of electronic structure: semicardinal and wavelet bases,"
    T.A. Arias, Reviews of Modern Physics 71:1, 267-311 (January 1999).

    and 

    "Robust ab initio calculation of condensed matter: transparent convergence through
    semicardinal multiresolution analysis,'' I.P. Daykov, T.A. Arias, and
    Torkel D. Engeness, Physical Review Letters, 90:21, 216402 (May 2003).

    For your convenience, preprints of the above articles may be obtained from
    http://arXiv.org/abs/cond-mat/9909130, 9805262, and 0204411, respectively.
*/

/*---------------------------  exc.c  -----------------------------------*
 *                                                                       *
 * Exchange-correlation energy density and deriv. versus n               *
 *                                                                       *
 *-----------------------------------------------------------------------*/
#ifndef DFT_EXC_H
#define DFT_EXC_H

void 
Dnexc_GGA(const RealSpaceScalarFieldColumn  &n,
	  const RealSpaceScalarFieldColumn  &Dx,
	  const RealSpaceScalarFieldColumn  &Dy,
	  const RealSpaceScalarFieldColumn  &Dz,
	  RealSpaceScalarFieldColumn &excpn);

void 
DDexc_GGA(int dir,
	  const RealSpaceScalarFieldColumn  &n,
	  const RealSpaceScalarFieldColumn  &Dx,
	  const RealSpaceScalarFieldColumn  &Dy,
	  const RealSpaceScalarFieldColumn  &Dz,
	  RealSpaceScalarFieldColumn &excpn);
void 
excprime_LDA(const RealSpaceScalarFieldColumn  &n,
             RealSpaceScalarFieldColumn &excpn);
void
exc_GGA(const RealSpaceScalarFieldColumn &n,
	const RealSpaceScalarFieldColumn &Dx,
	const RealSpaceScalarFieldColumn &Dy,
	const RealSpaceScalarFieldColumn &Dz,
        RealSpaceScalarFieldColumn &excn);

void
exc_LDA(const RealSpaceScalarFieldColumn &n,
        RealSpaceScalarFieldColumn &excn);

RealSpaceScalarFieldColumn exc_GGA(const RealSpaceScalarFieldColumn &n,
				   const RealSpaceScalarFieldColumn &Dx,
				   const RealSpaceScalarFieldColumn &Dy,
				   const RealSpaceScalarFieldColumn &Dz);

RealSpaceScalarFieldColumn exc_LDA(const RealSpaceScalarFieldColumn &n);

RealSpaceScalarFieldColumn Dnexc_GGA(const RealSpaceScalarFieldColumn &n,
				     const RealSpaceScalarFieldColumn &Dx,
				     const RealSpaceScalarFieldColumn &Dy,
				     const RealSpaceScalarFieldColumn &Dz);

RealSpaceScalarFieldColumn DDexc_GGA(int dir,
				     const RealSpaceScalarFieldColumn &n,
				     const RealSpaceScalarFieldColumn &Dx,
				     const RealSpaceScalarFieldColumn &Dy,
				     const RealSpaceScalarFieldColumn &Dz);

RealSpaceScalarFieldColumn excprime_LDA(const RealSpaceScalarFieldColumn &n);
//  New GGA code:
//vector ex_GC(vector &n);
//vector exprime_GC(vector &n);
//  New LSD code:
RealSpaceScalarFieldColumn exc_LSD_TETER(RealSpaceScalarFieldColumn &n_up, 
					 RealSpaceScalarFieldColumn &n_dn);
void excprime_LSD_TETER(RealSpaceScalarFieldColumn &n_up, 
			RealSpaceScalarFieldColumn &n_dn,
			RealSpaceScalarFieldColumn &excprime_up, 
			RealSpaceScalarFieldColumn &excprime_dn);

#endif // DFT_EXC_H