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/* Write an XCrysDen .bxsf Fermi surface file */
/* Copyright (c) 2020, 2025 MJ Rutter
*
* This program 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 3
* of the Licence, or (at your option) any later version.
*
* This program 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 this program; if not, see http://www.gnu.org/licenses/
*/
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include "c2xsf.h"
void bxsf_write(FILE* outfile, struct unit_cell *c, struct contents *m,
struct es *elect, struct kpts *kp,
struct symmetry *rs){
int i,j,k,ii,jj,kk,ic,off,ind,nb,ns;
double scale,lscale,frac1[3],chg,efermi;
int grid[3],gpts,nbands,nspins;
int *mapping;
frac1[0]=frac1[1]=frac1[2]=0;
scale=1;
if (flags&AU) scale=1/H_eV;
lscale=1;
if (flags&AU) lscale=BOHR;
if (!elect->eval)
error_exit("No evalues found, so cannot write bxsf");
/* Force kpoint co-ords to 0<=x<1 */
for(i=0;i<kp->n;i++)
for(j=0;j<3;j++)
kp->kpts[i].frac[j]=fmod(kp->kpts[i].frac[j]+1.0,1.0);
addabs(kp->kpts,kp->n,c->basis);
if (!elect->e_fermi){
efermi=NAN;
chg=elect->nel;
if (chg==0){
for(i=0;i<m->n;i++)
chg+=m->atoms[i].chg;
if ((chg)&&(elect->charge)) chg-=*elect->charge;
if (chg)
fprintf(stderr,"Assuming nel=%lf from total ionic charge\n",chg);
}
if (chg) efermi=calc_efermi(elect,kp,chg);
if (isnan(efermi)){
efermi=0;
fprintf(stderr,"Warning: no Fermi energy found\n");
}
else
fprintf(stderr,"Warning: using estimate of Fermi energy\n");
}
else efermi=*elect->e_fermi;
if (kp->mp){
for(i=0;i<3;i++) grid[i]=kp->mp->grid[i];
}
else{
grid_detect(kp,grid,frac1);
}
/* Check that the kpoint grid includes the gamma point */
if (!aeq(vmod2(frac1),0.0))
error_exit("Gamma point kpt must be included for .bxsf output");
gpts=grid[0]*grid[1]*grid[2];
if (gpts==0)
error_exit("Unable to deduce k-point mesh parameters");
mapping=malloc(gpts*sizeof(int));
if (!mapping) error_exit("Malloc error for mapping");
if (kgrid_expand(c,m,kp,rs,grid,frac1,mapping))
error_exit("Failed to unfold kpoints to regular grid");
fprintf(stderr,"nbspins=%d\n",elect->nbspins);
/* Count bands */
nbands=0;
for(i=0;i<elect->nbands;i++)
if (inrange(i+1,elect->band_range)) nbands++;
/* Count spins */
nspins=0;
for(i=0;i<elect->nbspins;i++)
if (inrange(i,elect->spin_range)) nspins++;
fprintf(outfile,"BEGIN_INFO\n");
fprintf(outfile,"# Generated by c2x\n");
if (m->title) fprintf(outfile,"# %s\n",m->title);
if (flags&AU)
fprintf(outfile,"# Units: Hartrees and Bohr^-1\n");
else
fprintf(outfile,"# Units: eV and Angstrom^-1\n");
if ((elect->nbspins>1)||(nbands!=elect->nbands)){
fprintf(outfile,"# Band number mapping\n");
fprintf(outfile,"# number label band spin\n");
i=1;
for(ns=0;ns<elect->nbspins;ns++){
if (!inrange(ns,elect->spin_range)) continue;
for(nb=0;nb<elect->nbands;nb++){
if (!inrange(nb+1,elect->band_range)) continue;
fprintf(outfile,"# %3d %4d %3d %1d\n",
i,nb+1+elect->nbands*ns,nb+1,ns);
i++;
}
}
}
fprintf(outfile," Fermi Energy: %.6f\n",efermi*scale);
fprintf(outfile,"END_INFO\n\n");
fprintf(outfile,"BEGIN_BLOCK_BANDGRID_3D\n");
fprintf(outfile,"Comment\n");
if (flags&AU)
fprintf(outfile,"BEGIN_BANDGRID_3D_Ha\n");
else
fprintf(outfile,"BEGIN_BANDGRID_3D_eV\n");
fprintf(outfile," %d\n",nbands*nspins);
fprintf(outfile," %4d %4d %4d\n",grid[0]+1,grid[1]+1,grid[2]+1);
fprintf(outfile," 0.0 0.0 0.0\n");
for(i=0;i<3;i++)
fprintf(outfile," % 8f % 8f %8f\n",c->recip[i][0]*lscale,
c->recip[i][1]*lscale,c->recip[i][2]*lscale);
for(ns=0;ns<elect->nbspins;ns++){
if (!inrange(ns,elect->spin_range)) continue;
for(nb=0;nb<elect->nbands;nb++){
if (!inrange(nb+1,elect->band_range)) continue;
fprintf(outfile," BAND: %3d",nb+1+elect->nbands*ns);
/* XCrysDen likes bizarre "general" grids */
ic=0;
for(i=0;i<=grid[0];i++){
ii=i%grid[0];
for(j=0;j<=grid[1];j++){
jj=j%grid[1];
off=jj*grid[2]+ii*grid[2]*grid[1];
for(k=0;k<=grid[2];k++){
kk=k%grid[2];
ind=kk+off;
if (ic%5==0) fprintf(outfile,"\n ");
fprintf(outfile," % 8f",elect->eval[nb+mapping[ind]*elect->nbands*elect->nbspins+elect->nbands*ns]*scale);
ic++;
}
}
}
fprintf(outfile,"\n");
}
}
fprintf(outfile,"END_BANDGRID_3D\n");
fprintf(outfile,"END_BLOCK_BANDGRID_3D\n");
free(mapping);
print_bandwidths(elect,kp);
}
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