I did not read the structure, but it is not a trivial problem. You have to choose among several different approaches, and may test all of them: 1) try to draw a molecule with "chemical sense" (may using "molecular" calculations") and only later try to fit in the solid state 2) substitute an atom with that of your interest in an already optimized structure and hope... 3) try to find a suitable "space" for an extra interstitial atom and hope...
None is expected to be straightforward, and all require a certain degree of "chemical experience"... HTH, Carlo 2015-02-25 3:18 GMT+01:00 Chenyang Lee <[email protected]>: > Dear experts in PWforum, > > I am experiencing difficulties relaxing some of the structures of B-HAp. > Because the Boron group substitutions are proposed (unknown), thus the > initial structure may deviate a lot from the final optimized one. Quantum > Espresso seems not to be very capable to do these jobs (no offense) and the > SCF cycles usually exceed 500 steps and it still cannot converge. > I am attaching the input file, and I’d appreciate it if someone who is > able to identify the problem can help me solve it. > > Thank you very much, > Chenyang > __ > Chenyang Li > Undergraduate Student, Materials Science and Engineering > The Pennsylvania State University, University Park > Phone: (814)441-4312 > > _______________________________________________ > > &control > calculation = 'vc-relax' > restart_mode = 'from_scratch' > prefix = ‘BHAp' > pseudo_dir = '/gpfs/home/col5422/work/HAp/pseudo/' > outdir = './scratch/' > tprnfor = .true. > forc_conv_thr = 1e-4 > etot_conv_thr = 1e-6 > nstep = 500 > / > &system > ibrav = 14 > A = 9.4166 > B = 9.4166 > C = 6.8745 > cosAC = 0.0 > cosAB = -0.5 > cosBC = 0.0 > nat = 52 > ntyp = 6 > ecutwfc = 40 > ecutrho = 400 > nosym = .true. > occupations = 'smearing' > smearing = 'gaussian' > degauss = 0.02 > / > &electrons > electron_maxstep = 500 > diagonalization = 'david' > mixing_mode = 'plain' > mixing_beta = 0.3 > conv_thr = 1e-6 > / > &ions > ion_dynamics = ‘damp' > / > &cell > cell_dynamics = ‘damp-pr' > / > > ATOMIC_SPECIES > H 1 H.pbe-kjpaw_psl.0.1.upf > B 1 B.pbe-n-kjpaw_psl.0.1.upf > C 1 C.pbe-n-kjpaw_psl.0.1.upf > O 1 O.pbe-n-kjpaw_psl.0.1.upf > P 1 P.pbe-n-kjpaw_psl.0.1.upf > Ca 1 Ca.pbe-spn-kjpaw_psl.0.2.3.upf > > ATOMIC_POSITIONS crystal > H 0.000000 0.000000 0.400000 > H 0.000000 0.000000 0.900000 > H 0.567369 0.551274 0.972591 > H 0.629383 0.851436 0.797858 > H 0.357078 0.434312 0.660517 > H 0.809237 0.663097 0.589841 > B 0.581602 0.618142 0.689068 > C 0.310984 0.129561 0.635342 > O 0.348000 0.259000 0.073000 > O 0.741000 0.089000 0.073000 > O 0.911000 0.652000 0.073000 > O 0.259000 0.911000 0.573000 > O 0.089000 0.348000 0.573000 > O 0.259000 0.911000 0.927000 > O 0.089000 0.348000 0.927000 > O 0.348000 0.259000 0.427000 > O 0.741000 0.089000 0.427000 > O 0.911000 0.652000 0.427000 > O 0.329000 0.484000 0.250000 > O 0.589000 0.466000 0.250000 > O 0.516000 -0.155000 0.250000 > O 0.534000 0.123000 0.250000 > O 1.155000 0.671000 0.250000 > O 0.877000 0.411000 0.250000 > O 0.484000 1.155000 0.750000 > O 0.466000 0.877000 0.750000 > O -0.155000 0.329000 0.750000 > O 0.123000 0.589000 0.750000 > O 0.000000 0.000000 0.250000 > O 0.000000 0.000000 0.750000 > O 0.603664 0.524999 0.843110 > O 0.718661 0.681136 0.557507 > O 0.546871 0.739153 0.774413 > O 0.441199 0.509454 0.566674 > O 0.464549 0.231819 0.634250 > O 0.235429 0.067896 0.472588 > O 0.237756 0.091652 0.804032 > P 0.400000 0.369000 0.250000 > P 0.631000 0.031000 0.250000 > P 0.969000 0.600000 0.250000 > P 0.369000 0.969000 0.750000 > P 0.031000 0.400000 0.750000 > Ca 0.333333 0.666667 0.001000 > Ca 0.666667 0.333333 0.501000 > Ca 0.666667 0.333333 0.999000 > Ca 0.333333 0.666667 0.499000 > Ca 0.246000 0.993000 0.250000 > Ca 0.007000 0.253000 0.250000 > Ca 0.747000 0.754000 0.250000 > Ca 0.754000 0.007000 0.750000 > Ca 0.993000 0.747000 0.750000 > Ca 0.253000 0.246000 0.750000 > > K_POINTS automatic > 4 4 4 1 1 1 > _____________________________________________ > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- ------------------------------------------------------------ Prof. Carlo Nervi [email protected] Tel:+39 0116707507/8 Fax: +39 0116707855 - Dipartimento di Chimica, via P. Giuria 7, 10125 Torino, Italy. http://lem.ch.unito.it/
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