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<p><span>Hi Akash,</span></p>
<p><span>I noticed multiple issues with your input file:</span></p>
<ol start="1" data-spread="true">
<li><code dir="ltr"><span>etot_conv_thr = 1.0d-06</span></code><span> is too strict for a structural relaxation and is set equal to the SCF convergence threshold. You can relax this criterion to the default value (around (10^{-4}) Ry), or at most (10^{-5}) Ry. I suggest trying (10^{-4}) first.</span></li>
<li>
<p dir="auto"><span>Is your system an insulator? If not, you should change</span></p>
<pre dir="ltr"><code dir="ltr"><span>occupations = 'fixed'</span></code></pre>
<p dir="auto"><span>to</span></p>
<pre dir="ltr"><code dir="ltr"><span>occupations = 'smearing'</span></code></pre>
<p dir="auto"><span>and choose an appropriate smearing scheme and width.</span></p>
</li>
<li><span>Do not mix different types of pseudopotentials. Use either </span><strong><span>all PAW</span></strong><span> or </span><strong><span>all ultrasoft</span></strong><span> pseudopotentials from the same library to ensure consistency and reliable results.</span></li>
</ol>
<p><span>Make these changes and see if you still encounter any errors.</span></p>
<p><span>Best,</span><br /><span>Amrendra</span></p>
<p><span>SRF, HBNI-RRCAT</span></p>
<p><br /></p>
<p id="reply-intro">On 2026-08-29 10:43, Akash Saxena via users wrote:</p>
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<p>Dear all users,etot_conv_thr = 1.0000000000d-06</p>
<p>Warm Greetings!</p>
<p>I have been calculating the formation energy for the double-cation perovskite system, FA(1-x)Cs(x)PbI3. I have taken x to be 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, and 1.</p>
<p>Out of these compositions, x=0.75 variable-cell relaxation calculation is not converging. I am sharing my input file below:- </p>
<p> &CONTROL<br /> calculation = 'vc-relax'<br /> etot_conv_thr = 1.0000000000d-06<br /> forc_conv_thr = 1.0000000000d-03<br /> prefix = 'facspbi3'<br /> tprnfor = .true.<br /> tstress = .true.<br /> nstep = 200<br /> verbosity = 'high'<br /> pseudo_dir = '/home/pmlab/akashsaxena/fapi/facspbi3/pseudopot'<br /> outdir = '/home/pmlab/akashsaxena/fapi/facspbi3/0.75/lda/outdir_1'<br />/<br />&SYSTEM<br /> degauss = 2.0000000000d-02<br /> ecutwfc = 6.0000000000d+01<br /> ibrav = 0<br /> nat = 54<br /> nosym = .false.<br /> ntyp = 6<br /> occupations = 'fixed'<br /> smearing = 'gaussian'<br />/<br />&ELECTRONS<br /> conv_thr = 1.0000000000d-06<br /> electron_maxstep = 200<br /> diagonalization = 'cg'<br />/<br />&IONS<br /> ion_dynamics = 'bfgs'<br />/<br />&CELL<br /> cell_dynamics = 'bfgs'<br />/<br />ATOMIC_SPECIES<br />Cs 132.905 Cs_pbe_v1.uspp.F.UPF<br />C 12.0107 C.pbe-n-kjpaw_psl.1.0.0.UPF<br />H 1.00794 H.pbe-rrkjus_psl.1.0.0.UPF<br />I 126.90447 I.pbe-n-kjpaw_psl.0.2.UPF<br />N 14.0067 N.pbe-n-radius_5.UPF<br />Pb 207.2 Pb.pbe-dn-kjpaw_psl.0.2.2.UPF<br />ATOMIC_POSITIONS crystal<br />H 0.7500000000 0.3734180000 0.7500000000<br />H 0.7500000000 0.8734180000 0.2500000000<br />H 0.9020890000 0.2876760000 0.7500000000<br />H 0.9020890000 0.7876760000 0.2500000000<br />H 0.8486280000 0.1624660000 0.7500000000<br />H 0.8486280000 0.6624660000 0.2500000000<br />H 0.6513720000 0.1624660000 0.7500000000<br />H 0.6513720000 0.6624660000 0.2500000000<br />H 0.5979110000 0.2876760000 0.7500000000<br />H 0.5979110000 0.7876760000 0.2500000000<br />Pb 0.0000000000 0.4927880000 0.0000000000<br />Pb 0.0000000000 0.4927880000 0.5000000000<br />Pb 0.0000000000 0.9927880000 0.0000000000<br />Pb 0.0000000000 0.9927880000 0.5000000000<br />Pb 0.5000000000 0.4927880000 0.0000000000<br />Pb 0.5000000000 0.4927880000 0.5000000000<br />Pb 0.5000000000 0.9927880000 0.0000000000<br />Pb 0.5000000000 0.9927880000 0.5000000000<br />C 0.7500000000 0.2881400000 0.7500000000<br />C 0.7500000000 0.7881400000 0.2500000000<br />I 0.2500000000 0.4986690000 0.0000000000<br />I 0.2500000000 0.4986690000 0.5000000000<br />I 0.2500000000 0.9986690000 0.0000000000<br />I 0.2500000000 0.9986690000 0.5000000000<br />I 0.7500000000 0.4986690000 0.0000000000<br />I 0.7500000000 0.4986690000 0.5000000000<br />I 0.7500000000 0.9986690000 0.0000000000<br />I 0.7500000000 0.9986690000 0.5000000000<br />I 0.0000000000 0.2420610000 0.0000000000<br />I 0.0000000000 0.2420610000 0.5000000000<br />I 0.0000000000 0.7420610000 0.0000000000<br />I 0.0000000000 0.7420610000 0.5000000000<br />I 0.5000000000 0.2420610000 0.0000000000<br />I 0.5000000000 0.2420610000 0.5000000000<br />I 0.5000000000 0.7420610000 0.0000000000<br />I 0.5000000000 0.7420610000 0.5000000000<br />I 0.0000000000 0.4848850000 0.2500000000<br />I 0.0000000000 0.4848850000 0.7500000000<br />I 0.0000000000 0.9848850000 0.2500000000<br />I 0.0000000000 0.9848850000 0.7500000000<br />I 0.5000000000 0.4848850000 0.2500000000<br />I 0.5000000000 0.4848850000 0.7500000000<br />I 0.5000000000 0.9848850000 0.2500000000<br />I 0.5000000000 0.9848850000 0.7500000000<br />N 0.8388620000 0.2415790000 0.7500000000<br />N 0.8388620000 0.7415790000 0.2500000000<br />N 0.6611370000 0.2415790000 0.7500000000<br />N 0.6611370000 0.7415790000 0.2500000000<br />Cs 0.2500010000 0.7845050000 0.7500000000<br />Cs 0.7500000000 0.2881400000 0.2500000000<br />Cs 0.2500000000 0.2881400000 0.2500000000<br />Cs 0.7500000000 0.7881400000 0.7500000000<br />Cs 0.2500000000 0.2881400000 0.7500000000<br />Cs 0.2500000000 0.7881400000 0.2500000000<br />K_POINTS automatic<br />3 3 3 0 0 0<br />CELL_PARAMETERS angstrom<br /> 13.1578080000 0.0000000000 0.0000000000<br /> 0.0000000000 12.7973780000 0.0000000000<br /> 0.0000000000 0.0000000000 13.1185190000<br /><br />In the output file, a large value for " negative_rho " is repeatedly reported, following which the program reports that the eigenvalues have not converged. I have attached a screenshot of the end of the output file to this email. <br />Could anyone suggest where I am going wrong in the input file? <br /><br /></p>
<p>Regards</p>
<p>Akash, Ph.D. Scholar, IIT Bombay.</p>
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