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zxzj05荣誉版主 (著名写手)
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[交流]
【求助】CG不收敛的问题
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我在计算声子谱时，经常碰到CG不收敛的问题，在abinit官方网站上的FAQ里面，也有人提出这个问题： During my calculation for the first derivative of the energy, after many iteration steps, the potential residual begins to fluctuate. It has been found that , due to the 'log file', this potential-based CG line minimization has trouble to converge. 有人提议： Sometimes the CG of WF have trouble converging ; especially for systems requiring very large ecut. In those case since the wave functions do not converge accurately the potential can't converge. To solve this you have to resort to an increase of "nline". nline=15 is a very safe value. Also you may increase nnsclo. 我做了下面修改： nline=15 nnsclo=25（不敢太大，非常浪费时间）， 可是错误依然出现。 请大家给点建设性意见，帮我度过难关！ 不胜感激！ [ Last edited by zxzj05 on 2008-12-5 at 10:33 ] |
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baoer3808
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5楼2009-04-20 09:11:09
2楼2008-12-04 22:23:02
zxzj05
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相关输入文件： # Crystalline phonon spectrum ndtset 10 #Set 1 : ground state self-consistency getwfk1 0 kptopt1 1 nqpt1 0 tolvrs1 1.0d-18 rfphon1 0 nline 15 nnsclo3 40 nnsclo4 40 #Q vectors for all datasets nqpt 1 qpt2 0.00000000E+00 0.00000000E+00 0.00000000E+00 ……………………………………………………………………………… qpt10 -2.50000000E-01 5.00000000E-01 2.50000000E-01 #Set 2 : Response function calculation of d/dk wave function iscf2 -3 # Need this non-self-consistent option for d/dk kptopt2 2 # Modify default to use time-reversal symmetry rfphon2 0 # Cancel default rfelfd2 2 # Calculate d/dk wave function only tolvrs2 0.0 # Cancel default for d/dk tolwfr2 1.0d-22 # Use wave function residual criterion instead #Set 3 : Response function calculation of Q=0 phonons and electric field pert. getddk3 2 # d/dk wave functions from last dataset kptopt3 2 # Modify default to use time-reversal symmetry rfelfd3 3 # Electric-field perturbation response only #Sets 4-10 : Finite-wave-vector phonon calculations (defaults for all datasets) getwfk 1 # Use GS wave functions from dataset1 kptopt 3 # Need full k-point set for finite-Q response rfphon 1 # Do phonon response rfatpol 1 3 # Treat displacements of all atoms rfdir 1 1 1 # Do all directions (symmetry will be used) tolvrs 1.0d-8 # This default is active for sets 3-10 nband 25 ecut 40 ngkpt 4 4 4 nshiftk 4 shiftk 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.5 iscf 5 错误输出： scfcge : ERROR - Potential-based CG line minimization not converged after 13 restarts. Action : read the eventual warnings about lack of convergence. Some might be relevant. Otherwise, raise nband. 增加nband，ecut只会增加计算量，浪费时间，无法真正解决问题。 |
3楼2008-12-05 10:58:38
wuchenwf
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6楼2009-04-20 19:22:42
