MOLCAS software

All calculations were carried out with the software MOLCAS-6.0 [16]. Scalar relativistic effects were included using a DKH Hamiltonian [14,15]. Specially designed basis sets of the atomic natural orbital type were used. These basis sets have been optimized with the scalar DKH Hamiltonian. They were generated using the CASSCF/CASPT2 method. The semi-core electrons (ns, np, n — 3,4, 5) were included in the correlation treatment. More details can be found in Refs. [17-19]. The size of the basis sets is presented in Table 1. All atoms have been computed with basis sets including up to g-type function. For the first row TMs we also studied the effect of adding two h-type functions. 

The MOLCAS program of Professor Bjorn Roos webpage teobor garm.teokem.lu.se A nice compendium of various softwares Is given In the appendix of reviews In ... 

Cl results can vary a little bit from one software program to another for open-shell molecules. This is because of the HF reference state being used. Some programs, such as Gaussian, use a UHF reference state. Other programs, such as MOLPRO and MOLCAS, use a ROHF reference state. The difference in results is generally fairly small and becomes smaller with higher-order calculations. In the limit of a full Cl, there is no difference. 

It is not possible to use normal AO basis sets in relativistic calculations The relativistic contraction of the inner shells makes it necessary to design new basis sets to account for this effect. Specially designed basis sets have therefore been constructed using the DKH Flamiltonian. These basis sets are of the atomic natural orbital (ANO) type and are constructed such that semi-core electrons can also be correlated. They have been given the name ANO-RCC (relativistic with core correlation) and cover all atoms of the Periodic Table.36-38 They have been used in most applications presented in this review. ANO-RCC are all-electron basis sets. Deep core orbitals are described by a minimal basis set and are kept frozen in the wave function calculations. The extra cost compared with using effective core potentials (ECPs) is therefore limited. ECPs, however, have been used in some studies, and more details will be given in connection with the specific application. The ANO-RCC basis sets can be downloaded from the home page of the MOLCAS quantum chemistry software (http //www.teokem.lu.se/molcas). 

MOLCAS, Electronic Structure Software, Almlof J, Blomberg M, Karlstrom G, Malmqvist P-A, Roos BO, Sadlej AJ, Siegbahn PEM, Widmark P-O... 

A method to deal with this problem was solved by P.-A. Malmqvist 20 years ago [64,65]. The method has become known as the CASSCF State Interaction (CASSI) method and is effective also for long CAS-CI expansions. It was recently extended to deal also with the integrals of the spin-orbit Hamiltonian [66]. The whole approach has been implemented in the latest version of the MOLCAS quantum chemistry software [67]. 

The excitation energies are obtained as the MS-CASPT2 energy difference between the excited state and the ground state computed with the same active space. The transition moments have been computed from the CASSCF wave functions. This is usually a reasonably accurate procedure. If the MS-CASPT2 treatment shows appreciable mixing between different CASSCF wave functions, we use instead these perturbation mixed functions (PM-CAS) to compute the transition properties. As we shall see, such a procedure becomes necessary for the Bi states. All calculations were performed using the MOLCAS quantum chemistry software [67]. 

A new set of calculations was performed for the present discussion. This were done on a Linux-equipped laptop. The MOLCAS quantum-chemistry software was used. The basis set was of the... 

Roos, B. O. These calculations were performed with the CASSCF module of the MOLCAS quantum chemistry software. The active space chosen was the 3d and orbital of each Cr atom (12) with 12 active electrons.. 

Aquilante F, De Vico L, Ferre N, Ghigo G, Malmqvist P-A, Neogrady P, Pedersen TB, Pitonak M, Reiher M, Roos BO, Serrano-Andres L, Urban M, Veryazov V, Lindh R (2010) Software news and update molcas 7 the next generation. J Comput Chem 31 224-247... 

---