This will be a not too specific comment and I have not looked into your atomic system, but if your system dimensions are too dissimilar; i.e., if the tube is too long, then you have a cycle of charge moving into and out of your Ni atom, this process gets larger the longer an asymmetric dimension is. I have seen this in multiple systems that have one direction that is, say, orders of magnitude larger than the other two. This could be aggravated if the forces are too large, this is, if the structural optimization is not very strict.
So I would look at forces first, and maybe approach the Ni atom slowly into the tube *by hand*, using the DM from the previous *ionic* step to get you going. Hopefully, these comments are useful. -Salvador ________________________________ From: siesta-l-requ...@uam.es <siesta-l-requ...@uam.es> on behalf of I. Camps <ica...@gmail.com> Sent: Thursday, November 29, 2018 11:23:50 AM To: siesta-l@uam.es Subject: Re: [SIESTA-L] [***Posible SPAM***]<< convergence problems BN+Ni >> Dear Leonardo, Thank you for your advise. Unfortunately, your suggestions did not work :( []'s, Camps On Wed, Nov 28, 2018 at 7:04 PM Leonardo Fonseca <fonsecal...@gmail.com<mailto:fonsecal...@gmail.com>> wrote: You could try a smaller mixing parameter. Currently you are using DM.MixingWeight 0.01. You could try 0.005 or even 0.001. If it works then you can increase it back to see at which value convergence is lost. Em ter, 27 de nov de 2018 às 19:02, I. Camps <ica...@gmail.com<mailto:ica...@gmail.com>> escreveu: Hello SIESTers, I am starting doing calculations with boron nitride nanotube interacting with nickel. My problem is that SCF calculations are not converging for even 1500 steps! I am using several mesh cutoff energies (between 150 and 650 Ry) but the problem persists. The input, pseudopotentials and output files are attached to this email (and can be download from the link https://drive.google.com/open?id=1s3Z-kQWcNptvGMX3pM7dbTR2FpVZLX74<https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_open-3Fid-3D1s3Z-2DkQWcNptvGMX3pM7dbTR2FpVZLX74&d=DwMFaQ&c=7ypwAowFJ8v-mw8AB-SdSueVQgSDL4HiiSaLK01W8HA&r=d_wByFh562xnF38KR6av_HxjWbFMw90KK5BKq2dwiQc&m=8vdXSd45w4M0hHp4CImKWXV-yNpYNLjf6GzeVD2y6A8&s=yp0Mc62NicI6eDUsFqLpn_757uWL9lVgtOFM-f4-pUU&e=>). Any help, ideas are welcome. Regards, Camps