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Dear Omar and Ivan,
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<div>I tried the several the setup you mentioned. Changing the startingwfc=“atomic” did not make difference, so it is not the starting point problem. However making the cpu parallel setting the same as gpu will give the same result as gpu. </div>
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<div>In all the other cpu calculation I use 128cores with -nk 1 -nb 8 -nd 1 . In the gpu calculation I use 8gpu cores with -nk 1 -nb 8 ; After I change the cpu parallel into 8cores with -nk 1 -nb 8 -nd 1 , the result became the same as gpu. </div>
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<div>My question is that if the parallel setting does make difference then is it the problem from compilation? </div>
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<div>Best</div>
<div>Shimin</div>
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<div># VBM CBM GAP</div>
<div>_________________CPU_____________________</div>
<div><b>60Ry_cpu</b></div>
<div><b>8.4785 11.5730 3.0945</b></div>
<div>60Ry_cpu_k111</div>
<div>8.4870 11.5774 3.0904</div>
<div><b><font color="#4ab6ff">60Ry_cpu_sameparallel</font></b></div>
<div><b><font color="#4ab6ff">8.6273 11.5295 2.9022</font></b></div>
<div><b><font color="#4ab6ff">60Ry_cpu_startingwfc_atomic</font></b></div>
<div><b><font color="#4ab6ff">8.4785 11.5730 3.0945</font></b></div>
<div>60Ry_NERSC7.0cpu</div>
<div>8.4298 11.5605 3.1307</div>
<div>_________________GPU_____________________</div>
<div><b>60Ry_gpu</b></div>
<div><b>8.6273 11.5295 2.9022</b></div>
<div>60Ry_gpu_k111</div>
<div>8.5993 11.5521 2.9528</div>
<div>60Ry_gpu_smallermixing</div>
<div>8.6273 11.5295 2.9022</div>
<div><font color="#1c95ff">60Ry_gpu_startingwfc_atomic</font></div>
<div><font color="#1c95ff">8.6273 11.5295 2.9022</font></div>
<div>60Ry_NERSC7.0gpu</div>
<div>10.2121 10.7435 .5314 : broken module</div>
<div>60Ry_othergpu</div>
<div>8.6273 11.5295 2.9022</div>
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<div>70Ry_gpu</div>
<div>8.6350 11.5408 2.9058</div>
<div>80Ry_gpu</div>
<div>8.6301 11.5394 2.9093</div>
<div>________________GPU Unit cell__________</div>
<div>80Ry_gpu_uc</div>
<div>8.4537 11.5622 3.1085</div>
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<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">60Ry_gpu_uc</div>
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">8.4585 11.5537 3.0952</div>
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<blockquote type="cite">
<div>On Jul 30, 2024, at 6:06 AM, Ivan Carnimeo <icarnimeo@sissa.it> wrote:</div>
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Dear Shimin,</div>
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unfortunately the test is too large also for me to try it.</div>
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Small differences on band gap and total energy can be also due to differences in MPI parallelism used in the CPU and GPU calculations.</div>
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If you want to understand more, you can launch the CPU calculation with exactly the same parallelization options as the GPU one (number of MPI ranks, OMP threads, pools, bands, etc...). This will tell you much the error depends on the different CPU/GPU libraries
or on the different MPI distribution of the data.</div>
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You can also reduce the randomness of the wavefunction initialization with startingwfc='atomic'.</div>
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Regards,</div>
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IC</div>
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Quantum ESPRESSO community stands by the Ukrainian</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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and expresses its concerns about the devastating</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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that the Russian military offensive has on their</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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and on the free and peaceful scientific, cultural,</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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economic cooperation amongst peoples</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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