From owner-chemistry@ccl.net Fri Mar 31 00:49:01 2023 From: "Cheng Fei Phung feiphung-,-hotmail.com" To: CCL Subject: CCL: accurate computation for active and inactive orbitals Message-Id: <-54878-230331004730-12169-JpMPgdbZ2G8habh+z+wiIQ++server.ccl.net> X-Original-From: "Cheng Fei Phung" Date: Fri, 31 Mar 2023 00:47:29 -0400 Sent to CCL by: "Cheng Fei Phung" [feiphung#hotmail.com] Could anyone provide accurate computation for active and inactive orbitals to be used in https://qiskit.org/documentation/nature/locale/bn_BN/stubs/qiskit_nature.second_q.transformers.FreezeCoreTransformer.html and https://qiskit.org/documentation/nature/stubs/qiskit_nature.second_q.transformers.ActiveSpaceTransformer.html ? My current inaccurate solution is using HOMO-LUMO approach. See https://github.com/tencent-quantum-lab/tensorcircuit/issues/120#issuecomment-1457932770 I am looking at https://www.scm.com/doc/BAND/index.html which seems to provide [some DFT methods](https://i.imgur.com/mHeWCtl.png) to do so. However, I do not have access to SCM software. Any suggestions ? From owner-chemistry@ccl.net Fri Mar 31 14:58:00 2023 From: "Christine Isborn cisborn{}ucmerced.edu" To: CCL Subject: CCL: TDDFT and Excited States Summer School and Workshop: June 29-July 8 Message-Id: <-54879-230331145341-25068-UUo0GP2r1/fDmX3B7m0VTA a server.ccl.net> X-Original-From: "Christine Isborn" Date: Fri, 31 Mar 2023 14:53:39 -0400 Sent to CCL by: "Christine Isborn" [cisborn/./ucmerced.edu] We are organizing the 3rd iteration of the US-based TDDFT and Excited States Summer School and Workshop to take place at Rutgers, Newark June 29th-July 3rd 2023, and encourage students to apply! Information about the school will be posted here (https://sites.rutgers.edu/tddft/) as it becomes available. At the Summer School, students will experience a combination of lectures and hands-on computational lessons to learn about DFT and TDDFT fundamentals, nonadiabatic dynamics, as well as how to model excitations of molecules in the condensed phase and excitations in extended systems. We are still fundraising for student support, so don't know yet how much of the costs of housing and travel we will be able to cover. After the School, a Workshop focusing on current research in TDDFT and excited states will be held with invited speakers presenting on July 5th-8th. Please share this information with students and postdocs who you think might be interested in this opportunity. To apply to the summer school, students should upload their CV and a 200-word statement to the following google form: https://docs.google.com/forms/d/e/1FAIpQLSdQlAZsddAyU8g4Sb9h- A2uutDYxs3wevUZ9yKd8QBFtBvoWg/viewform A separate email request will be sent to the advisor requesting a support letter. We hope to receive all applications by April 10th and plan to let students know if they are chosen to attend the school by May 1st. Please reach out to us with any questions!, Adam Wasserman, Andre Schleife, Carsten Ullrich, Christine Isborn, Michele Pavanello, and Neepa Maitra From owner-chemistry@ccl.net Fri Mar 31 17:01:00 2023 From: "Susi Lehtola susi.lehtola() alumni.helsinki.fi" To: CCL Subject: CCL: accurate computation for active and inactive orbitals Message-Id: <-54880-230331104751-18315-NY27tO5Q59gzTll3edI9WA-x-server.ccl.net> X-Original-From: Susi Lehtola Content-Language: en-US Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Fri, 31 Mar 2023 17:47:34 +0300 MIME-Version: 1.0 Sent to CCL by: Susi Lehtola [susi.lehtola-$-alumni.helsinki.fi] On 3/31/23 07:47, Cheng Fei Phung feiphung-,-hotmail.com wrote: > > Sent to CCL by: "Cheng Fei Phung" [feiphung#hotmail.com] > Could anyone provide accurate computation for active and inactive orbitals to be used in https://qiskit.org/documentation/nature/locale/bn_BN/stubs/qiskit_nature.second_q.transformers.FreezeCoreTransformer.html and > https://qiskit.org/documentation/nature/stubs/qiskit_nature.second_q.transformers.ActiveSpaceTransformer.html ? > > My current inaccurate solution is using HOMO-LUMO approach. See https://github.com/tencent-quantum-lab/tensorcircuit/issues/120#issuecomment-1457932770 > > I am looking at https://www.scm.com/doc/BAND/index.html which seems to provide [some DFT methods](https://i.imgur.com/mHeWCtl.png) to do so. > > However, I do not have access to SCM software. > > Any suggestions ? There is a common misunderstanding here by what is meant by 1) active and inactive orbitals in many-electron calculations, 2) the selection of the active space orbitals, and 3) the use of a frozen core in ADF. 1. the active and inactive orbitals in many-electron calculations refer to whether substitutions from/to the orbital is allowed when building the many-electron basis, similarly to the complete active space (CAS) method which is what quantum simulators are approximating. One builds the Hamiltonian and diagonalizes it in the space of active orbitals, only. 2. the choice of the active space orbitals is a complicated issue, mostly because of limitations of classical computers. Unoccupied orbitals of Hartree-Fock theory are often a bad starting point due to the incorrect form of the potential experienced by the virtual orbitals in Hartree-Fock theory. Many alternatives have been suggested in the literature, ranging from Improved Virtual Orbitals to the use of natural orbitals from a lower level of theory, such as Møller-Plesset perturbation theory truncated at the second order (MP2) or configuration interaction singles and doubles (CISD). The latter class of methods is available in PySCF, for example, for which Qiskit has an interface; see the PySCF documentation for how to build the density matrices and natural orbitals. 3. the frozen core orbitals in ADF refer to their behavior in self-consistent field (SCF) calculations, meaning here Hartree-Fock and density functional theory. Since the core orbitals are much lower in energy, polarization effects in a chemical environment are smaller for them than for the valence orbitals, which is the foundation for freezing the core orbitals to the atomic form. This is also the foundation for the pseudopotential and effective core potential approaches. Susi -- ------------------------------------------------------------------------------ Mr. Susi Lehtola, PhD Academy of Finland research fellow susi.lehtola*_*helsinki.fi Associate professor, computational chemistry http://susilehtola.github.io/ University of Helsinki, Finland ------------------------------------------------------------------------------ Susi Lehtola, FT akatemiatutkija susi.lehtola*_*helsinki.fi dosentti, laskennallinen kemia http://susilehtola.github.io/ Helsingin yliopisto ------------------------------------------------------------------------------