Relativistic four-component MRCISD+Q calculations of the six lowest valence states of molecular [Formula: see text] anion including breit interactions

Luiz Guilherme Machado de Macedo; Yasmin Celen de Castro Vieira; Rhuiago Mendes de Oliveira; Ricardo Gargano

doi:10.1007/s00894-023-05564-x

Relativistic four-component MRCISD+Q calculations of the six lowest valence states of molecular [Formula: see text] anion including breit interactions

J Mol Model. 2023 Jun 13;29(7):207. doi: 10.1007/s00894-023-05564-x.

Authors

Luiz Guilherme Machado de Macedo¹, Yasmin Celen de Castro Vieira², Rhuiago Mendes de Oliveira³, Ricardo Gargano⁴

Affiliations

¹ Campus Centro Oeste Dona Lindu, Universidade Federal de São João Del Rei, Rua Sebastião Gonçalves Coelho, 400, Divinópolis, 35501-296, Minas Gerais, Brasil. lgm@ufsj.edu.br.
² Campus Centro Oeste Dona Lindu, Universidade Federal de São João Del Rei, Rua Sebastião Gonçalves Coelho, 400, Divinópolis, 35501-296, Minas Gerais, Brasil.
³ Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, Av. João Alberto, 1840, Bacabal, 65700-000, Maranhão, Brasil.
⁴ Instituto de Física, Universidade de Brasília, P.O. Box 04455, Brasília, 70919-970, Distrito Federal, Brasil.

PMID: 37310506
DOI: 10.1007/s00894-023-05564-x

Abstract

Context and results: This study aimed to obtain potential energy curves within a multireference 4-component relativistic method and to present spectroscopic constants (R[Formula: see text],[Formula: see text],[Formula: see text]x[Formula: see text],[Formula: see text]y[Formula: see text], D[Formula: see text], D[Formula: see text], B[Formula: see text],[Formula: see text],[Formula: see text],[Formula: see text] ), accurate extended Rydberg analytical form, and rovibrational levels for the 6 low-lying states of the I[Formula: see text] anion. For these states, some spectroscopic constants, rovibrational levels, and an accurate analytical form are presented for the first time in literature, and they are of interest for femtosecond and dynamics experiments of I[Formula: see text] as well as for electron attachment of I[Formula: see text]. This study suggests that the inclusion of relativistic and correlation effects treated at the MRCISD+Q level is needed to obtain reliable results, specially for D[Formula: see text].

Computational and theoretical techniques: The potential energy curves of the ground and the excited states of the molecular iodine anion (I[Formula: see text]) were investigated at multireference configuration interaction (MRCISD) with Davidson size-extensivity correction (denoted as +Q) within a fully relativistic four-component relativistic framework including Breit interaction.

Keywords: 4-component calculations; Breit interaction; Excited states; Extended rydberg function; MRCISD calculations; Molecular iodine anion (I); Relativistic effects.